United States 

Environmental Protection 

Agency 

Office Of Water EPA 833-B-89-100 

(4203) August 1989 

EPA POW Sludge Sampling And 

Analysis Guidance Document 
TABLE OF CONTENTS 

Page 

ACKNOWLEDGEMENTS ............................................ vi 

1. INTRODUCTION ........................................... 1-1 

2. SLUDGE SAMPLING ........................................ 2-1 

2.1 BACKGROUND INFORMATION............................ 2-1 

2.1.1 

2.1.2 

2.2 SAMPLE 

2.2.1 

2.2.2 

2.3 SAMPLE 

2.3.1 

2.3.2 

2.4 SAMPLE 

2.5 SAMPLE 

Solids Content and Viscosity ............... 2-1 

Processed Sludge Characteristics ........... 2-2 

2.1.2.1 Anaerobically Digested Sludge ..... 2-2 

2.1.2.2 Aerobically Digested Sludge ....... 2-3 

2.1.2.3 Dewatered Sludges ................. 2-3 

2.1.2.4 Compost Product ................... 2-3 

2.1.2.5 Dried Powder ...................... 2-3 

POINT SELECTION ............................ 2-4 

General Considerations ..................... 2-4 

2.2.1.1 Sample Point Representation of 

the Entire Sludge Stream .......... 2-4 

2.2.1.2 Availability of Flow Data and/or 

Solids Data ....................... 2-7 

Sludge Sample Points ....................... 2-8 

COLLECTION ................................. 2-8 

Sampling Equipment ......................... 2-11 

Proper Sampling Practices .................. 2-12 

SIZE, SAMPLE TYPE, AND SAMPLING FREQUENCY .. 2-14 

PREPARATION AND PRESERVATION ............... 2-19 

Sample Container Material .................. 2-20 

Sample Container Preparation ............... 2-20 

Sample Preservation ........................ 2-21 

Holding Time Prior to Analysis ............. 2-22 

2.5.1 

2.5.2 

2.5.3 

2.5.4 

2.6 PACKAGING AND SHIPPING................................. 2-22 

2.6.1 Packaging .................................. 2-22 

2.6.2 Transportation Regulations ................. 2-22 

iii 
TABLE OF CONTENTS (Continued) 

Page 

2.7 DOCUMENTATION..................................... 2-24 

2.7.1 Sample Labeling ............................ 2-24 

2.7.2 Chain-of-Custody ........................... 2-26 

2.7.3 Sampling Log Book .......................... 2-27 

2.8 SAFETY CONSIDERATIONS.............................. 2-27 

3. ANALYTICAL PROCEDURES................................. 3-1 

3.1 CONVENTIONAL AND INORGANIC POLLUTANT PARAMETERS... 3-2 

3.2 METALS ........................................... 3-6 

3.2.1 Analyte Isolation/Preparation Overview..... 3-6 

3.2.2 Analytical Techniques for Metals........... 3-8 

3.2.2.1 Sample Preparation/Digestion ...... 3-8 

3.2.2.2 Analytical Detection Methods ...... 3-9 

3.3 ORGANICS . . . . . . . . . . . . . . . . . . . . . . . . . . 3-18 

3.3.1 Overview of Analyte Extraction and 

Isolation.................................. 3-18 

3.3.2 Recommended Analytical Techniques for 

Organics................................... 3-22 

3.3.2.1 Methods 1624C and 1625C ........... 3-23 

3.3.2.2 Methods 624-S and 625-S ........... 3-25 

3.4 PATHOGENIC MICROORGANISMS.......................... 3-26 

4. QUALITY ASSURANCE...................................... 4-1 

5. SAMPLING AND ANALYTICAL COSTS.......................... 5-1 

5.1 MANPOWER REQUIREMENTS ............................. 5-1 

5.2 IN-HOUSE ANALYTICAL COSTS ......................... 5-2 

5.3 CONTRACT ANALYTICAL COSTS ......................... 5-4 

5.4 SAMPLING EQUIPMENT COSTS .......................... 5-4 

5.5 Opportunities for Cost Savings .................... 5-7 

6. REFERENCES............................................. 6-1 

A. APPENDIX A: Chain of Custody Form...................... A-1 

B. APPENDIX B: Determination of Volatile Solids Reduction. B-1 

iv 
LIST OF TABLES 

Table 

2.1 

2.2 

2.3 

2.4 

2.5 

3.1 

3.2 

3.3 

3.4 

3.5 

3.6 

5.1 

5.2 

Sludge Flow Measurement Devices ....................... 

Sludge Sampling Paints ................................ 

Containers, Preservation, Holding Times, and Minimum 

Sample Volume ......................................... 

Potential Interferences Associated with Sampling 

Shipping and Storage .................................. 

Standard Preservatives Listed in the Hazardous 

Materials Table (49 CFR 172.101) Used by EPA for 

Preservation of Water, Effluent, Biological, Sediment 

and Sludge Samples .................................... 

Analytical Techniques for Conventional and Inorganic 

Pollutants in Sludge .................................. 

Recommended Preparation Technique for Elemental 

Analysis of Sludge Samples ............................ 

Comparison-Summary of ICAP and AAS .................... 

Recommended Inductively Coupled Wavelengths and 

Estimated Instrumental Detection Limits ............... 

Atomic Absorption Flame and Furnace Instrumental 

Detection Limits for Wastewater Samples .............. 

Analytical Techniques for Determination of Pathogenic 

Microorganisms in Sewage Sludge ....................... 

Sampling Manpower Needs ............................... 

Typical Contract Analytical Costs for Commonly 

Analyzed Sludge Parameters ............................ 

Page 

2-9 

2-9 

2-15 

2-23 

2-25 

3-3 

3-10 

3-12 

3-14 

3-16 

3-29 

5-2 

5-5 

V 
ACKNOWLEDGMENTS 

This guidance document was completed under the direction of 

Cristina Morrison, of the U.S. EPA's Office of Water Enforcement 

and Permits (OWEP), with assistance from Tom Wall, also of OWEP. 

This document was prepared by Science Applications International 

Corporation (SAIC) under EPA Contract No. 68-01-7043. The 

document was revised to address peer review comments under EPA 

Contract No. 68-C8-0066. 

The SAIC Work Assignment Manager was Werner H. Zieger. 

Significant contributions were made by Jorge McPherson, John 

Sunda, and Mark Klingenstein. 

This document has been peer reviewed. EPA wishes to 

acknowledge the valuable review and comments provided by the 

following entities: 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

• 

EPA Region 3 

EPA Region 5 

EPA Region 9 

EPA Region 10 

EPA Environmental Monitoring Support Laboratory 

AMSA 

California State Water Resources Control Board 

Connecticut Department of Environmental Protection 

Eli Lilly and Company 

Eugene Oregon Public Works Department 

LA County Sanitation District 

Missouri Department of Natural Resources 

Nampa, Idaho Wastewater Division 

Ohio EPA 

Unified Sewerage Agency of Washington County 

John F. Morrison, P.E., American Society of Quality 

Control Engineers 
1. INTRODUCTION 

The passage of the 1987 amendments to the Clean Water Act 

brought about significant changes in the regulation of the use 

and disposal of municipal sewage sludge. Although the Clean 

Water Act had required since 1977 that EPA develop technical 

standards for sludge use and disposal, the 1987 amendments 

required that these standards, when promulgated, be implemented 

through permits. The amendments also state that prior to 

promulgation of the technical standards, EPA must include sludge 

conditions in NPDES permits issued to publicly-owned treatment 

works or take other appropriate measures to protect public health 

and the environment from pollutants in sewage sludge. This 

requirement has initiated a program for "case-by-case" permitting 

to ensure protection of the environment prior to the issuance of 

final sludge standards which are scheduled for promulgation in 

October 1991. 

This focus on sludge permitting places increased emphasis on 

the need to assess sewage sludge quality. In policy and guidance 

documents that EPA has developed for implementing the sludge 

requirements of the Clean Water Act, the Agency has recommended 

that POTWs sample and analyze their sludge at least annually to 

determine if the sludge quality is such that the sludge may be 

safely reused and recycled or disposed. Accurate characterization of sludge composition spots operational problems at the 

treatment works and may also signal adverse environmental 

impacts. In addition, sludge sample and analysis is needed to 

assess compliance with current requirements (e.g., 40 CFR Part 

257 requirements for cadmium and PCBs). 

1-1 
In view of the variability of municipal sludge quality, 

appropriate procedures must be followed to collect and analyze 

samples that accurately represent each POTW's sludge quality. 

This manual was developed to provide that guidance to POTW 

operators, engineers, managers, chemists and permit writers. It 

was intended to provide guidance in developing and implementing a 

sampling and analysis program, to gather information on sludge 

quality and determine compliance with permit conditions. This 

manual is based on current, state-of-the-art field and laboratory 

practices and therefore is recommended for all sludge sampling 

and analysis programs. 

1-2 
2. SLUDGE SAMPLING 

2.1 BACKGROUND INFORMATION 

Depending on the use or disposal practice, it may be 

necessary to sample various sludge types throughout a given POTW. 

In order to sample a sludge stream effectively, it is necessary 

for sampling personnel to be aware of the physical 

characteristics of the sludge stream(s) at intended sampling 

locations. 

2.1.1 Solids Content and Viscosity 

Two important physical characteristics of sludge with 

respect to sampling and analysis are viscosity and solids 

content. Solids content is the percent, by weight, of solid 

material in a given volume of sludge. Sludges have a much higher 

solids content than most wastewaters. Solids content and solids 

settling characteristics determine whether a given sludge will 

separate into different fractions which increases the potential 

of obtaining a nonrepresentative sample. 

Viscosity is the degree to which a fluid resists flow under 

an applied force. The viscosity of a sludge is only somewhat 

proportional to solids content. This property affects the 

ability to automatically sample a liquid, since friction through 

pipes is proportional to liquid viscosity. In general, sludges 

of up to 20 percent solids may be conveyed by means of a pump. 

Sludge with a greater solids content, often referred to as sludge 

cake, must be conveyed by mechanical means. Automatic samplers 

that rely on pumps may be useful only for liquid sludges with a 

solids content of less than 20 percent. However, sludge cakes 

require manual grab sampling. Other problems created by sludge 

2-1 
solids (see Section 2.3.1) generally preclude the use of automatic samplers. 

Solids content is also significant from an analytical standpoint. Increased solids content may require sample dilution and 

cause a corresponding increase in experimental error and 

detection limits. Also, water removal through dewatering can 

either concentrate parameters of interest in the sludge and 

increase analytical accuracy, or carry away pollutants and 

decrease pollutant concentration and analytical accuracy. 

Analytical precision (repeatability) and accuracy (closeness to 

true value) may also decrease as the concentration of interfering 

compounds and matrix effects increase, due to higher solids 

content after dewatering. 

2.1.2 Processed Sludge Characteristics 

The quantity and quality of sludge generated depends on raw 

wastewater characteristics and the sludge treatment practices. 

The sludge to be sampled may be in the form of a liquid, 

dewatered cake, compost product, or dried powder. Some of the 

physical characteristics of each sludge type are described below. 

2.1.2.1 Anaerobically Digested Sludge 

Anaerobically digested sludge is a thick slurry of 

dark-colored particles and entrained gases. When well digested, 

it dewaters easily and has a non-offensive odor. The addition of 

chemicals coagulates a digested sludge prior to- mechanical 

dewatering. The dry residue of digested sludge contains 30 to 50 

percent volatile solids. Depending on the mode of digester 

operation, the percent solids of digested sludges ranges from 4 

to 8 percent. 

2-2 
2.1.2.2 Aerobically Digested Sludge 

Aerobically digested sludge is a dark-brown, flocculent, 

relatively inert waste produced by long-term aeration of sludge. 

The suspension is bulky and generally difficult to thicken. The 

odor of aerobically digested sludge is not offensive. The 

percent solids of aerobically digested sludge is less than that 

of the influent sludge (if not decanted), because approximately 

50 percent of the volatile solids are converted to gaseous end 

products during aerobic digestion. 

2.1.2.3 Dewatered Sludges 

Dewatering converts sludge from a flowing mixture of liquids 

and solids to a cake-like substance more readily handled as a 

solid. The characteristics of dewatered sludge depend on the 

type of sludge, chemical conditioning, and treatment processes 

employed. The percent solids content of dewatered cake ranges 

from 15 to >40 percent. Cake with a lower percent solids is 

similar to a wet manure, while cake with a higher percent solids 

is a chunky solid. 

2.1.2.4 Compost Product 

Composting is a process in which organic material undergoes 

biological degradation to a stable end product. Properly 

composted sludge is a sanitary, nuisance-free, humus-like 

material containing 75 to 80 percent solids. Approximately 20 to 

30 percent of the volatile solids are converted to carbon dioxide 

and water. 

2.1.2.5 Dried Powder 

Dried powder is the residue from heat drying processes. 

Sludge drying reduces water content by vaporization of water to 

permit sludge grinding, weight reduction, and to prevent 

2-3 
continued biological action. The moisture content of dried 

sludge is less than 10 percent. 

Incinerator ash is a product of the incineration of sewage 

sludge. Ash is therefore not covered under the sampling or 

analysis of sewage sludge. It is covered under RCRA Subtitle C 

if it is a hazardous waste and if not it falls under Subtitle D. 

2.2 SAMPLE POINT SJZLECTION 

2.2.1 General Considerations 

NPDES, pretreatment and sludge program officials need sludge 

quality data in order to determine whether sludge use or disposal 

may pose a threat to public health or the environment. Thus, as 

a general rule, sludge samples should be drawn from an 

appropriate sampling point and in such a manner that the sample 

represents, as well as possible, the quality of the sludge as it 

will be disposed of or used. When selecting a specific sample 

point, the following two factors should be carefully considered: 

0 Does the sample point represent the entire sludge 

stream? 

0 Are the sludge stream flow or mass flux data available? 

The following paragraphs examine both factors and present 

recommendations on means to address each factor. 

2.2.1.1 Sample Point Representation of the Entire Sludge Stream 

Often it is not possible to obtain a wholly representative 

sample of a given wastestream at any one time. Effort must be 

made, however, to ensure that a sample is obtained that is as 

representative as possible. Three cLncerns that need to be 

2-4 
addressed to ensure that the sample points selected will provide 

representative samples of the entire sludge stream are: 

obtaining samples that are representative of the cross-section of 

the entire flow; obtaining well mixed samples; and obtaining 

samples of multiple sludge streams. 

A particular concern in any sampling program is to obtain 

samples which represent the entire flow past the sample point 

throughout the sample period. Each discrete sample should 

represent the cross-section of the entire flow at the sampling 

point. Each composite sample of multiple contributory streams 

should represent the cross-section of the entire flow of the 

combined stream. 

Samples should be obtained from points where the sludge is 

well-mixed. While some pollutant parameters are predominantly 

associated with the solids fraction (particularly precipitated 

metals), others are more associated vith the liquid-fraction 

(many dissolved organics). Failure to acquire a sample with 

representative solid/liquid fractions can significantly affect 

the analytical results of a given sample. This is particularly 

true of sludge streams wit:? high percent solids and large flee 

particles. Since turbulence ensures mixed samples, these 

recommendations should be followed: 

0 In sludge processing trains, samples from taps ,on the 

discharge side of sludge pumps are well mixed since 

flow at this point in the system is turbulent with no 

solids separation within the flow stream. 

0 If a sample is drawn from a tap on a pipe containing 

sludge which is distant from the sludge pumps, the 

average flow velocity through the pipe should be 

greater than 2 feet per second (fpsl. Average 

velocities of less than 2 fps result in solids 

separation and settling, and affect samr;le solids 

content, depending on the location of the tap (top, 

2-5 
side or bottom of the pipe). Given a choice, a tap on 

the side of the pipe is preferable. In addition, the 

tap should be a large size to encourage draw from the 

entire cross-section of flow when fully open. 

At times it may be necessary to sample a poorly mixed open 

channel flow. If this cannot be avoided, then each sample must 

be a composite consisting of grabs taken at several levels (l/4, 

l/2 and 3/4 depth, for example) in order to minimize sample bias 

caused by solids stratification. For sampling solid sludges 

(i.e. dewatered cake, compost, etc.), stratification can be 

avoided by not only sampling at various depths, but at numerous 

locations over the entire sludge pile. 

Although it is preferable to sample sludge just prior to its 

exit from the treatment plant in a combined stream, sometimes 

that is not possible. Therefore, a consideration in many sludge 

sampling situations is the need to produce a composite sample 

from confluent streams. PLn example is the sampling of sludge 

flows from several parallel sources which later combine 

downstream in an unsafe or inaccessible location. Several 

options exist to accommodate multiple streams. The most 

appropriate choice depends on the sludge flow and solids flux 

information available, the parameters being sampied and the 

purpose of the generated data. Several options are as follows: 

0 The simplest oFtion is to withdraw equal volumes of 

sample from each of the multiple sludge streams tc 

create a composite sample. This approach is justified 

in the case of identical units receiving equal flow and 

generating equal sludge amounts. 

0 A second option is to weight the grab samples in each 

composite according to the wastewater flow to each unit 

(or in the case of filter cake, the thickened sludge 

flow to each unit;. This approach recognizes that for 

different sized units ;rith different design flows, the 

volume of sludge produced *dill theoretically be 

2-6 
proportional to the influent flow to the unit. 

However, factors such as unequal loading rates, 

differences in sludge collection mechanisms, etc. can 

affect solids removal rates and sludge generation rates 

by unequal, parallel treatment units. This option 

particularly applies to situations where no sludge flow 

or solids data exists for unequa: parallel flow 

streams. 

0 The third option is to weight grabs from individual 

streams based on sludge flow data or solids flux data. 

Nhether to use sludge flow or solids flux will depend 

on the sample streams, the parameters of interest, and 

the planned use of the resulting data. For example, if 

filter cake is being monitored for compliance ;ylith land 

applicati.on limits, solids flux data would be used as 

the criteria for proportioning grabs from parallel 

dewatering systems, since most land appiication limits 

are based on dry weight application rates. 

2.2.1.2 Availability of Flow Data and/or Solids Flux Data 

The availability of accurate solids flux data (weighti'time; 

or accurate flow data (volume/time) is an Inportanc, consideration 

in planning a sludge sampling program. Most information 

requirements relating to sludge characteristics involve, at least 

in part, the need for data on the solids flux of 2o;lutant 

parameters found in sludge discharged from a ?073~. T3e 3erclnt - - - 

solids should be determined on sludge sampies. 

Portable flow monitoring devices are not well suited to 

high-solids flow streams, and most sludge prccessing streams are 

not designed in a manner which is physicall;r conducive to the use 

of these devices. Thus, in most cases, it is necessary tc rely 

on existing integrated flow monitoring equipment. Due to 

difficulties in monitoring sludge flows, flow meters are high 

maintenance items. Frequent calibration of sludge flowmeters is 

necessary in order to ensure accurate flow measurement. This 

data should be cross -checked agair_;t mass balance data. ~Xhen 

ultimate use cr disposal practices dictate monic,oring sludge with 

2-7 
a high solids content, liquid flow meters are replaced by gross 

weight scales. Table 2.1 summarizes the types of flow 

measurement equipment employed to monitor various sludge flows. 

2.2.2 Sludcre SamDle Points 

The determination of the appropriate sludge sampling point 

is dependent on the rationale behind the sampling. For permits 

and regulation enforcement, sludge samples must come from the 

treatment unit process immediately preceding disposal or use. 

For example, if a POTS disposes of its dewatered filter cakes in 

a sanitary landfill, then sampling activity focuses on the output 

sludge stream from the dewatering device (i.e., vacuum filter, 

belt filter, etc.). The sludge treatment processes commonly 

employed are stabilization, dewatering, drying, cornposting, and 

thermal reduction. Table 2.2 surmnarizes sampling points for 

these processes. Other sludges sampling points may be necessary 

to examine the origin or fate of pollutants within a POT,, (i.e., 

additional sludge samples from influent and output of other 

processes may be needed). 

2.3 SAMPLE C3LLXTION 

Having selected appropriate sampling points for a sludge 

sampling program, it is then necessary to determine the method 

and equipment by which sampling *dill be.carried out. In ccing 

so I the following objectives should be considered: 

0 Each grab sample, or aliquot of a composite sample, 

must be as representative as possible of the total 

stream flow passing the sampling point 

0 Effort must be made to minimize the possibility of 

sample contamination 

0 The selected sampling method should be safe, convenjent 

and efficient. 

2-8 
TABLE 2.1. SLUDGE FLOFi MEASUREMENT DEVICES 

Aoplication 9easurement Means 

Stabilized Sludge Venturi 

Flow Tube 

Magnetic Meter 

Positive Displacement Pump 

Thickener Magnetic Meter 

Positive Displacement Pump 

Dewatering Belt press scales 

Drying 

Composting 

Bulk container or truck scales 

Thermal Reduction 

TABLE 2.2. SLUDGE SAMPLING POINTS 

Sludge TvDe Samplins Point 

Anaerobically Sample from taps on the discharge side of 

Digested - positive displacement pumps. 

Aerobically 

Digested - 

Sample from taps on discharge lines from pumps. 

If batch digestion is used, sa-rtple directly 

from the digester. Twc cautions'are in order 

concerning this practice: 

(1) If aerated during sampling, air .entrains in 

the.sample. Volatile organic compounds may 

purge with escaping air. 

(2) When aeration is shut off, solids separate 

rapidly in well digested sludge. 

Thickened 

Sludges - 

Sample from taps on the discharge side of 

positive displacement pmps. 

2-9 
TABLE 2.2. SLUDGE SAMPLING POINTS 

(continued) 

Sludge Tvoe Samolins Point 

Heat Treatment Sample from taps on the discharge side of 

positive displacement pumps after decanting. 

Be careful when sampling heat treatment 

sludge because of: 

(1) High tendency for solics separation 

(2) High temperature of sample 

(frequently >60°C as sampled) can 

cause problems with certain sample 

containers due to cooling and 

subsequent contraction of entrained 

gases. 

Dewatered, Dried, Sample from material collection conveyors 

Composted, or and bulk containers. Sample from many 

Thermally Reduced locations within the sludge mass and at 

various depths. 

Dewatered: 

Belt Filter Press, 

Centrifuge, Vacuum 

Filter Press 

Sludge Press 

(plate and frame) 

Drying Beds 

Sample from sludge discharge rhute. 

Sample from the storage bin; select 

four points within the storage bin, 

collect equal amount of sample from 

each point and combine. 

Divide bed into quarters, arab equal 

amounts of sample from the center of 

each quarter and combine to form a 

grab sample of the total bed. Each 

grab sample should include z;?e 

entire depth of the sludge (<own to 

the sand). 

Compost piles Sample directly from front-end 

loader as the sludge is beins loaded 

into trucks to be hauled away. 

2-10 
Except for limitations on the use of automatic sampling 

devices, the actual,sampling techniques for sludges are similar 

to those found in wastewater sampling. The following sections 

describe two important considerations for selecting appropriate 

sludge sampling methods: sampling equipment and proper sampling 

practices. 

2.3.1 Samnlins Ea-uioment 

In general, automatic sampling devices, which are widely used 

for wastewater streams, do not work well for sludge streams 

because of the solids content and viscosity of sludges. 

Automatic samplers which use pumps to draw samples up a suction 

tube cause solids separation if flow velocity in the suction and 

discharge tube iS too low. This increases pump head requirements 

and limits the range of tubing diameter. A second problem which 

occurs in the use of automatic samplers is fouling of tubing 

and/or pump structure by sludge solids. This results in 

contamination of subsequent aliquots during composite sampling. 

Sludge particles may also plug the sample tube or pumpAng 

mechanism and interrupt sample collection. Yherefora, it is 

preferable to sample liquid sludge streams manually, partic-Jlarly 

if sample taps can be provided on pump discharge lines. 

Sampling equipment must be made of materials 'Nihich vi11 not 

contaminate or react with the sludge. The best material choices 

are Teflon, glass, and stainless steel because they are 

relatively inert. When the cost of Teflon and stainless steel 

equipment prohibits or restricts their use, plastic, steel and/or 

aluminum may be substituted for most sampling activities. (If 

steel equipment is used, ensure that galvanized or zinc coated 

items are not used because these materials will readily release 

zinc into the sample.1 

2-11 
Graduated glass or plastic pitchers or cylinders are used to 

draw grabs for manually composted samples. Stainless steel 

pitchers are also commercially available, and are used to grab 

samples from taps and also can be affixed to lengths of conduit 

to sample from open channel flows. Only aluminum conduits should 

be used since most commercially available steel conduit is 

galvanized. In addition, only stainless steel clamps should be 

used to attach the sample container to the conduit. 

2.3.2 Proper Sampling Practices 

Listed below are practices that should be followed ;Ihen 

sampling sludges: 

0 

0 

0 

0 

0 

Clean all sampling equipment between each sample period 

to prevent cross-contamination. Cleaning consists of 

thorough washing with a laboratory detergent, thorough 

rinsing with tap water and then ;rith at least three 

distilled water rinses. 

Sample aiiquots should be composted directly into 

sample containers. Sample containers, preservation of 

sample and allowable holding time pyior tc analysis are 

discussed in Section 2.5. 

When collecting samples for oil and grease anal:Jsis, 

sample directlv into the sample container since cil and 

grease tend to adhere to surfaces. Sample composites 

should be sent t,o the laboratory as a series of grab 

samples. 

Sampie collecti on procedures should be adequar,oly 

documented, as discussed in Secticn 2.7. 

When collecting samples for organic volatiles or semivolatiles, carefully pour liquid sludge into ccntainer 

so as to avoid entrapping air *d:thin sample. -,,1 c; 1 

container to overflowing and screw on 11c!. Check air 

bubbles by turning container upside down and tapping 

lid. If air bubbles rise, open container and fill Xlth 

additional sample. For sludge cake, care-fully pack 

sludge ir,:o container so as to avoid air spaces. Fill 

the container to overflowing and screld on iid. 

2-i2 
0 When collecting samples for dioxin/furan, fill the 

container to 4/5 full to enable expansion of samples 

when they are frozen. 

0 When collecting samples for pesticides/PCBs/herbicides, 

metals and nonconventionals, fill container to within 

l/2 inch of the top to provide room for expansion 

should there be any gas production during sample 

shipment. 

When sampling liquid sludges: 

0 To draw a fresh representative sludge sample from a 

tap: 

a) Allow sufficient time following pump start up to 

clear line of stagnant sludge, and 

b) Allow sludge to flow for several seconds from tap 

prior to sampling in order to flush out stagnant 

sludge and solids accumulated in the tap. 

0 Before drawing a sludge sample, rinse each piece of 

sampling equipment 3 times with sample to reduce the 

chance of contamination from the previous grab. 

0 To prevent solids separation in the sample, use glass, 

Teflon-coated stirring rods, or stainless steel spoons 

to mix the sample before splitting or transferring any 

portion of it to another container(s.1. 

When sampling solid sludges: 

0 For either dewatered cakes, dried powder or compost 

prcduct, combine equal amounts collected"at various 

locations/depths for each grab sample to obtain a more 

representative sample. 

a) To produce a sample from multiple sample locations 

(e.g., two or more dewatering units), combine the 

grab samples from each location (equal amounts or 

weighted based on flow or solids flux data) in a 

plastic or stainless steel pail and thoroughly mix 

the sample (with a scoop or spoon), then transfer 

it to sample containers. This is not appropriate 

for volatile or microbial samples. 

2-13 
b) When sampling drying beds, divide each bed into 

quarters. From the center of each quarter, 

collect a single core sample through the entire 

depth of the sludge using a coring device. 

Usually a small amount of sand will be collected; 

avoid large amounts of sand. Combine and 

thoroughly mix in plastic or stainless steel pail 

and transfer to sample containers. 

2.4 SAMPLE SIZE, SAMPLE TYPE, AND SAMPLING FREQUENCY 

Sample Size 

A proper sample is small enough to transport conveniently 

and handle carefully in the laboratory, but large enough to 

accurately represent the characteristics of the whole material. 

Minimum sample sizes required for accurate analysis are specified 

in each analytical method. Table 2.3 lists minimum sample sizes 

for some common analytical methods. For methods not listed here, 

consult an analytical methods reference or the laboratory for 

further guidance. 

Sample Tvpe 

A grab sample collected at a particular time and location 

can represent the composition of the source only at that time and 

location. In the case of most sludges, single grab samples will 

adequately represent only the instantaneous composition of the 

material being sampled. The quality of a grab sample xi:1 be 

improved if it is comprised of several smaller samples taken over 

a period of a few minutes. 

A composite sample gives a better reflection of the timeand location-weighted average concentrations that are found in 

the sludge flow stream. In most cases, the term "composite 

sample8' refers to a mixture of grab samples collected at the s,ne 

sampling point at different times. Although a 24-hour composite 

2-14 
'l'ABT,F 2. 3 

CONTATNERS, PRESERVATION, IIOI,D1‘NG TIMES, AND MINIMUM SAMPLE V6LUMES(') 

-__--.. 

Parameter 

Wide-moutlred 

Container 

- 

Pr-eservative(*) 

Maximum 

Holding Time (2) 

.-... 

IInorganic Coinpoun& 

Asbestos p, 

Meta& 

Chromium VI 

Mercury 

P,G 

P ,G 

Metals except. above P,G 

Qrqanic Compounds 

Extractables (including 

phthalatcs, nitrosamines, 

nitroaromatics, isophorone, 

polynuclear aromatic HC, 

haloethers, chlorinated 

tlC and TCDD) 

G, teflonlined cap 

P, for 

dioxin and 

furan 0111~ 

Extr-actable (phenols) 

Purqeablcs (Halocarbons 

,lnd Aromatics 1 

Puryeai) I es 

(Atrroleiin and 

Act-ylorl i t r i le ) 

None 

cool, 4OC 

HN03 to pHt2 

HN03 to pH<2 

Cool, 4OC 

0.008% Na2Y203 

Coo1 , 4Oc 

LI2SO4 to pH<2 

0.008% Na2S203 

None 2000 mL 

24 hours 

28 days 

6 months 

7 days (ill 40 days (a) 

300 mL 

500 mL 

1000 mL 

1000 mL 

7 days b.qto) 

14 days in 

darkness 

1.4 clays 

1000 mL 

>20 mL 

;20 ml, 
TABLE 2.3 (Continued) 

CONTAINERS, PRESERVATION, HOLDING TIMES, AND MlNIMUM SAMPLE VOLUMES(' 

Wide-mouthed 

Parameter Container Preservative(*) 

Maximum (2) 

Holding Time 

Pesticides 6, PCBs C! teflon- Cool 4Oc 1000 mL 

lined septa 0.008% Na2S203 

(1) 

(2) 

40 CFR Part 136 

Preservatives should he added to sampling containers prior to actual sampling 

episodes. Holding times commerlce upon addition of sample to sampling container. 

Shipping of pre-preserved containers to the sample sites may be regulated under DOT 

hazardous materials regulations. Shipping of preserved samples to the laboratory 

is generally not regulated as a hazardous material. 

(3) Varies with analytical method. Consult 40 CFR Part 136, 

P= Plastic (Polyethylene) 

(; x Glass (Non-etched Pyrex) 

(a) Atter extraction 

(u) Before extraction 

(w/o) Without preservatives 
sample (consisting of a number of time- or flow-weighted grab 

samples) is more representative than a grab sample, it can give a 

picture of only one day's sludge quality. Historical data is 

necessary to truly represent the sludge quality. A composite for 

volatile components analysis is produced in the lab from grab 

samples collected in the field. 

Samplinc Freo-uencv 

As sludge quality is directly related tc wastewater influent 

quality (which can vary from day to day and hour to hour),,a POTW 

should sample and analyze its sludge frequently to cbtain 

representative data. Collection of representative sludge data is 

crucial because the permitting authority will use the resultant 

analytical data to establish permit monitoring parameters and 

frequencies, and thereafter, to assess compliance with the permit 

and to ascertain if there is a potential for adverse environmental impacts. POTW operators should be aware that EPA's 

"Strategy for Interi!! Implementation in Permits Issued to ?OT?Js" 

(draft June 1988) to be finalized during the fourth quarter of 

1989) sets forth minimum recommended mcnitorlng frequencies to be 

included in the NPDES permit when it Ls reissued. The Interim 

Strategy is scheduled to be finalized in the summer of 1989. The 

NPDES permit ;Jriter may decide based on hisiher best professicnal 

judgment (BP;) that more frequent monitoring is needed. The 

sampling frequency will be set out in the POTX's permit. 

To the extent practicable, the POT% should have a sludge 

sampling program k'hich adequately addresses random and cyclic 

variation within the system and the potential for human exposure 

to sludge once it is disposed of or used. 

0 Anticipated cyclical variation in pollutant loadings - 

although they are difficult tc accurately predict, 

anticipated cycles include daily industrial production 

2-17 
cycles, weekly industriai production cycles, and other 

known or suspected production cycles, particularly 

those associated with intermittent batch discharges by 

significant industries. Longer-term production cycles, 

including seasonal and annual/multi-year production 

cycles (e.g., business cycles!, do not need to be 

considered in determining monitoring frequency unless 

they are known to affect short-term variation in sludge 

quality. 

0 Risk of environmental exposures - As the risk of 

environmental exposure from sludge use/disposal 

increases, a PO'IW should increase its sampling 

frequency to provide better information about potential 

variation in sludge quality. For example, a sludge 

that is applied to food-chain croplands should be 

sampled more frequently than sludge that is disposed of 

in a landfill that has an impermeable liner and a 

groundwater monitoring system. 

Other factors that should be considered in determining 

sampling frequency include: 

0 Size - As influent flow increases, day-to-day sludge 

variability increases, as does outflow volume. Thus, 

where high volumes exist, the risk of adverse exposure 

is higher. Since variability and potential impact are 

major considerations, many sampling programs are based 

on size alone (e.g. 40 CFR Part 503 proposed rule). 

Size is also an easy factor to measure. 

0 Percentage of industrial flow - hXile sludge quality 

variability is directly related to the individual 

characteristics of each POTW, POTws ;lith little or no 

commercial/industrial contributors in the system can 

expect relatively small variation in sludge qua1lt.y. 

POTWs with significant industri al contributions can 

expect to have monthly, weekly and even daily -variation 

in sludge quality. 

0 Treatment plant characteristics - As either detention 

time or mixing increases within a treatment plant, 

sampling frequency can be reduced since treatment 

processes will effectively composite sludge to a 

greater degree. For example, high rate digestion and 

storage/blending facilities will provide mechanical 

mixing of sludge. Other plant technologie such as 

anaerobic digestion, aerobic digestion and Storage, 

2-18 
provide longer sludge detenti.on times, enabling greater 

mixing through physical processes such as diffusion, 

convection, etc. For combined sewer systems, a 

sampling strategy may be designed to monitor the 

effects of storm events on sludge quality. 

Another consideration is the type(s) of information a POTW 

wishes to collect. If, for example, a POTW desires to measure 

daily variation over a typical week, the POTW may collect and 

analyze seven or more 24-hour composite samples for the 

pollutant. Similarly, if a POTW wishes to measure variation 

within a single day, the POTW may collect and analyze several 

grab samples taken at different times curing the day. 

2.5 SAMPLE ?REPARATION AND PRESERVATION 

There is the potential for errors of varying severity to be 

introduced during Sample collection and storage which affect 

analytical determinations. To avoid potential errors and 

maintain sample integrity, POTW operators should carefully 

consider the following: 

0 Sample Container Yaterial 

0 Sample Container Preparation 

0 Sample ?reservation 

0 Holding Time Prior to .Analysis. 

Table 2.3 lists recommended container materials, 

preservatives, holding times, and minimum sample volumes for the 

analysis of sludges. For method-specific details concerning all 

facets of sample preparation and preservation, consult the 

references cited in 40 CFR Part 136, "Guidelines for Establishing 

Test Procedures for the Analysis of Pollutants." 

2-19 
2.5.1 Sample Container Material 

The requirements for sample containers are method-specific, 

but containers are usually made of Teflon, glass or polyethylene. 

Sample containers should be wide-mouthed for sludge sampling, 

particularly for solids Icake) sampling. Teflon containers are 

typically supplied with Teflon caps. Glass containers frequently 

are supplied with caps which can cause sample contamination 

(phenol, phthalate compounds). For organic parameters, these 

glass container caps should be fitted with Teflon liners; 

aluminum liners could be used but they must be fitted precisely 

within the circumference of the cap to prevent tearing and 

possible sample leakage. 

2.5.2 Sample Container Preparation 

Proper sample container preparation is necessary to prevent 

contamination of the sample by material left from the container 

manufacturing process or that has otherwise been introduced into 

the unused sample containers. All containers should be uashed 

with a good qua lity laboratory detergent, thoroughly rinsed -;ith 

tap wat ---, 0~ and then rinsed at least 3 times with distilled ';ater 

prior to air drying. Additional container preparations for 

analysis of particular parameters are described below: 

0 Extractable Organics - I;se glass containers with 

Teflcn-lined caps only. Wash containers as above an3 

rinse with solvent (typically nethylene chloride) ; airdry. 

0 Volatile Organics - Prepare containers by washing and 

rinsing as described above, and then bake both vials 

and septums at 105'C until dry. Cool in an 

organic-free atmosphere. 

0 Metals - Wash and rinse as described above. Then rinse 

*dith dilute acid cl part deionized, distilled *dater to 

1 part nitric acid !HNGJ j, followed by t;lo rinses ~5th 

deionized, distilled water. 

Z-20 
2.5.3 Sample Preservation 

Table 2.3 presents U.S. EPA?s recommended preservation 

protocols. These protocols are primarily intended for effluent 

monitoring; however, they are generally appiicable to liquid 

sludge sampling. 

The following are specific recommendations regarding sample 

preservation: 

0 In instances where it is desirable to split one 

composite sample into several fractions, each having 

incompatible preservation requirements, it is 

acceptable to chill the entire sample to 4°C during 

compositing. Following the sample period, the 

composite is then cautiouslv mixed and split into 

various fractions, each of which is appropriately 

preserved. This does not apply to samples for analysis 

of volatile, semivolatile or microbial contaminants. 

0 If processing of microbial samples cannot occur within 

one hour of collection, iced coolers should be used for 

storage during transport to the lab. Samples should be 

held below 10°C during the maximum transport time of 6 

hours. Note: these samples must be immediately 

refrigerated and processed at the lab sjlthin 2 hours cf 

receipt. 

3 Xhenever possible, sample containers should be 

pre-preserved. Thus, grab samples are preserved upon 

sampling and ccmposite samples are preserved during 

compositing. This is not appropriate, however, Then 

sampling for metals or pathogens. 

0 In general, all samples should be chilled (4°C) during 

cornpositing and holding. 

0 For solid sludge samples (cake), adding chemical preservative is generally not *useful since the 

preservative usually does not penetrate the slu_dge 

matrix. Preservation consists of chilling to ?'C. 

0 When sampling and holding sludges, particu'arlkbiologically active sludges, gas production in the 

sealed container may Cause an explosion unless the 

pressure is periodically released. This should not be 

2-21 
2.5.4 

done however if volatile or semivolatile pollutants are 

to be analyzed. 

Holdinq Time Prior to AnalVSiS 

Table 2.3 lists the maximum holding times for various 

pollutant samples. Table 2.4 lists some potential interferences 

that may affect samples during shipping and storage. There are 

many more interferences associated with particular analytical 

methods, which are discussed further in chapter 3 as well as in 

the particular methodology. 

2.6 PACXAGING AND SHIPPING 

When analysis will be performed away from the sampling 

locale, samples must be packaged and transported. 

2.6.1 Packaqinq 

Sample containers must be packaged in order to protect them 

and to reduce the risk of leakage. Containers should be held 

upright and cushioned from shock. In addition, sufficient 

insulation and/or artificial refrigerant ("blue ice") shculd be 

provided to maintain a sample temperature of 4'C for the duration, 

of transportation. 

2.6.2 TransDortation ReUUlatiOnS 

The following guidelines control the shipment of xastewater 

and sludge samples: 

. . 

0 Unpreserved normal (i.e., not heavily contaminated) 

environmental samples are not regulated under DCT 

Hazardous Material Regulations. These samples may be 

shipped following the packaging guidelines in Section 

2.6.1, and using a commercial carrier, etc. To ass-;lre 

proper sample temperature, transit time should be held 

to less than 24 hours. 

2-22 
TABLE 2.4 

POTENTIAL INTZRFERENCES ASSOCIATED WITH 

SAMPLE SHIPPING AND STO-RAGE 

Parameter Interferences' Prevention 

Acidity Carbon dioxide loss 

Ammonia Chlorine 

Volatilization 

Cyanide 

Chromium VI 

Phenols 

Silica 

Sulfide 

Sulfite 

Organic 

Chemicals 

Sulfides 

Reducing agents 

Hydrogen sulfide, 

Sulfur dioxide 

Oxidizing agents 

Aeration, agitation 

Aeration, agitation 

Photodegradation 

Fill container completely 

Sodium thiosulfate 

Fill container completely 

Cadmium nitrate, tetrahydrate 

Minimize holding time 

Aerate 

Ferrous sulfate 

Avoid freezing 

Fill container completely 

Fill container completely 

Use Srown glass container 

1 Other than those addressed by protocols shown in Table 2.3 
0 When environmental samples are preserved as recommended 

(see Table 2.51, they may be shipped as non-hazardous 

samples. 

The guidelines above assume no material is present in the 

samples at concert,, +T-ations ;Ihich would result in a flhazardousfl DOT 

rating. Should hazardous material (as defined by DOT) be 

present, DOT regulations concerning packaging, transportation and 

labeling must be followed Isee 49 CFR parts 172, 173 and 178). A 

material is considered hazardous hy DOT if it fails one of the 

four characteristic tests of: corrosivity, ignitability, 

reactivity and EP Toxicity [see "Test Xethods for Evaluating 

Solid Waste, SW 846, 1986 for exact methods]. Municipal sewage 

sludges labeled as hazardous are usually from failed EP Toxicity 

tests and occasionally from reactivity tests. 

2.7 DOCUMEXTATION 

Adequate documentat ion of sludge sampling activities (1) is 

important for general program qualit y assurance/quality control, 

and (2) is req-ulred by most monitoring regulations. Proper 

sampling activity documentation includes proper sample labeling, 

chain-of- custody procedures and a log book of sampling 

activities. The number of people in the chain of cu.st,ody shculd 

be kept to a minimum to limit the possibility of contamination 

and to increase accountability. 

L. 7 7.1 Sample Labelinq 

It .-is important that each sample label include the following 

information iitems In bold text are minimum elements!: 

0 Sampling Organizaticn Xame 

0 Facility Name (being sampled) 

0 Bottle Number (specific to container 

2-24 
TABLE 2.5 

STANDARD PRESERVATIVES LISTED IN THE HAZARDOIJS MATERIALS TABLE (49 CFR 172.101) 

USED BY EPA FOR PRESERVATION OF WATER, EFFLUENT, BIOLOGICAL, SEDIMENT, AND SLIJDGE SAMPLES 

_.____ -___ -- . . -. -.--- 

Sample Type/ 

Parameter Preservative 

-- _____I- ----_--. 

Organic Carbon fiydrochloric acid 

Nitrogen Species Mercuric chloride 

Metals, lfardness** Nitric acid 

Nitrogen Species Sulfuric acid 

COD, Oil & Grease, 

P (hydrolyzable) 

Organic Carbon 

Quantity of 

Pf-I Preservative Added WT. % of 

Recommendation Per Liter* Preservative 

c2 ->l 2 ml of 1:l 0.04% 

N.A. 40 mg 0.004% 

<2 - >1 5 ml of Cont. (70%) 0.35% 

(2 - >l 2 ml of 36N 0.35% 

Cyanides sodium hydroxide >12 - (13 2 ml of 10N 0.080% 

Phenolias Ortho-phosphoric acid <4 - >2 to yield desired pH 

Biological - Fish & Freezing O*C N.A. N.A. N.A. 

SlJellfish Tissue*** (Dry Ice) 

~_~ -. .-___-_._. - ___ ___ 

* 

kk 

kkk 

Sample dilution must be avoided. The volume of washings must be minimized and any 

dilution that does occur must be documented and the data corrected for the dilution. 

The sample may be initially preserved by cooling and immediately shipping it to the 

laboratory. Upon receipt itr the laboratory, the sample must be acidified with cont. 

ffNOwit d 

to pH<Z. At time of analysis, sample container should be thoroughly rinsed 

1 : lfJNC13 ;washings shOllld be iJddt?tl to SdlIl~-‘~~. 

Dry ice is classified ;Is s3Jl ORM-A Jlazard by DOT. There is no labeling requirement 

for samples preserved with dry ice, but each package moist be plainly and durably 

marked on at least one side or edge with the desigrlation ORM-A. Advance arrangements 

which must be met: to sllip tlr-y ice ;II-~ fou~~tl in DOT regulation 49 CFR 173.616. 
Sample Number (specific to sampling event i.e. location) 

Type of sample, i.e., grab, 24 hour composite, etc. 

Date, Time (24 hour time is preferable, i.e., 1600 vs. 

4:00 p.m.1 

Sample Location 

Preservatives 

Analytical Parameter(s) 

Collector 

Special Conditions or Remarks. 

Labels and ink should be waterproof. Fix labels to ccntainers with clear waterproof tape. Tape completely around 

container and over label to prevent accidental label loss or ink 

smear during shipping and handling. 

2.7.2 Chain-of-Custody 

Each sample shipment requires a chain-of-custody record. A 

chain-of-custody document provides a record of sample transfer 

from person to person. This document helps protect the integrity 

of the sample by ensuring that only authorized persons have 

custody of the sample. In addition, the chain-of-custody 

procedure ensilres an enforceable record of sample transfer ~b.=ict= 

is necessary if the sample results are to be used in a judicial 

proceeding alleging violations of sludge standards. Tl-liS 

document shall record each sample's collection and 3and1inc 

history from time of collection until analysis as Yell as t:ie 

information listed on each sample bottle. All personnel 3&ndlinc 

the sample shall sign, date and note the time of day on the 

. 

chain-of-custody document. A sample chain-of-c?Jstody dot.nent Is 

provided in Appendix A. 

2-26 
2.7.3 Samnlins Log Book 

All sampling activities should also be documented in a bound 

log book. This book duplicates all information recommended for 

the chain-of-custody document above, and notes all relevant 

observations regarding sample stream conditions. 

2.8 SAFETY CONSIDERATIONS 

Safety is important in sludge sampling, especially since 

many sampling points preclude direct collection of grab samples, 

Several safety considerations are noteworthy given the potential 

health-related effects of sewage and sludge, and the hazards 

associated with treatment plant equipment (water, electricity, 

moving components, etc.). 

Personal hygiene is important for all personnel involved in 

sludge sampling efforts. Sludge presents a unique health hazard, 

not only because of the potential presence of toxic substances, 

but also because of the abundance of pathogens (bacteria, viruses 

and worms). As a precautionary measure, inoculations are 

recommended for all personnel who have direct contact with sludge 

(as well as any wastewater) samples. As a ,minimu.m, inoculation 

should include diseases such as typhoid and tetanus. Avcidance 

of direct sl.Jdge contact is preferred and is possible if proper 

precautions are taken. Wear rubber or latex gloves at all times, 

especially while collecting or handling samples, and use 

waterproof garments when the risk of splashing exists. Kash any 

cuts or scrapes thoroughly and treat immediately. 

Gas production from biclogically active sludge samples may 

cause pressure build UP, especially if the samples are not stored 

at 4'c as recommended in Table 2.3. Treating samples with the 

appropriate preservatives (e.g., acids for metals samples) as 

2-27 
well as refrigeration will significantly suppress biological 

activity and therefore gas evolution. However, except for 

volatile and semi-volatile analysis samples, pressure may need to 

be periodically released to prevent explosions of the sealed 

sampling containers. The field control sample should also be 

vented to expose it to the same potential contaminants. 

There are several universal safety precautions that are 

applicable to sludge sampling as well. 'When sampling sludge in 

confined areas, particularly around anaerobic digesters, 

dangerous gases may be present. These gases may include either 

explosive vapors (methane), poisonous mixtures (including 

hydrogen sulfide), or oxygen-deprived atmospheres (carbon 

dioxide). Explosive vapors require care to avoid sparks and 

possible ignition. These situations necessitate adequately 

ventilated equipment, gas detection meters and backup breathing 

apparatus. Exercise care around open pits or uncovered holes. 

Proper lighting increases the visibility of such hazards. Loose 

or dangling garments (ties, scarves, etc.) should not be worn 

around equipment with moving parts, especially pumps. Zxercise 

extra awareness around pumps contrclled by intermittent timers. 

Finally, be very careful when sampling high pressure sludge lines 

or lines containing high temperature, thermally-ccnditioned 

sludges (i.e., Zimpro or Porteus) in order to avoid injury by 

either high pressure streams or burns. 

z-28 
3. ANALYTICAL PROCEDURES 

Sewage sludge is compositionally diverse, rich in organic 

matter; and highly variable in physical and chemical properties. 

Sewage sludge analysis is difficult because of the inherent 

complexity of sludge matrices. Matrix complexity often results 

in significant analytical interference which can lead to poor 

analytical accuracy and precision with a resultant loss of data 

reliability. For example, matrix interference, which is 

exacerbated in sludges, can both mask the identity of analytes by 

suppressing instrumental response, or falsely contribute to a 

positive response. 

Variations in the physical and chemical properties of sewage 

sludge often make it difficult to obtain samples which represent 

the material as a whole. The diversity of sludge 

characteristics, coupled with the heterogeneous nature of 

sludges, presents a considerable challenge to precise and 

accurate determinations of trace levels of pollutants in sludges. 

Often sludge samples must be diluted to attain analytical 

results. A tenfold sample dilution means a tenfold increase in 

the detection limit (e.g., 1 ppm to 10 ppm). This increases the 

complexity of attaining accurate, precise data. 

The following sections provide a summary of the analytical 

techniques available for characterization of the sewage sludge 

and soil constituents considered important in the selection of 

use or disposal options. Analytical techniques for conventional 

pollutants, inorganics, priority pollutant metals, priority 

pollutant organics, and pathogenic organisms are discussed. 

3-1 
3.1 CONVENTIONAL AND INORGANIC POLLUTANT PARAMETERS 

Conventional pollutant parameters have historically been the 

focal point of sewage sludge analyses. The parameters normally 

associated with this group include total suspended solids, pH, 

oil and grease, BOD and fecal coliform. Inorganics, which have 

also been of concern, include phosphorus species, nitrogen 

species, phenolics, and total cyanide. As Table 3.1 indicates, 

the analytical protocols commonly employed for these analyses are 

adaptations of gravimetric or calorimetric techniques developed 

for aqueous samples. 

Existing federal regulations (40 CFR Part 257) require POTWs 

that apply sludge to food-chain croplands to measure the pH of 

the sludge-soil mixture and background soil cation exchange 

capacity (CEC). Soil pH should be measured using a 1:1 solution 

of sludge-soil mixture and deionized sister (see Table 3.1). For 

distinctly acid soils, CEC should be measured using the summation 

method (see Table 3.1). For neutral, saline, or calcareous 

soils, the sodium acetate method should be used (see Table 3.1;. 

Another inorganic of more recent concern is asbestos. 

Asbestos is a generic term which refers to naturally occurring, 

commercially useful fibrous silicate mineral. There are two 

types. Chrysotile, which comprises 93 percent of the current 

asbestos production, is a hydrated magnesium silicate which 

exhibits a much higher cancer risk for textile workers. 

Amphibole, which occurs in five forms, crocidolite, amosite, 

actinolite, tremolite and anthrophyllite, is a hydrated silica 

associated with various lung carcinogenic trace metals (nickel, 

chromium, aluminum and iron). Crocidolite poses the greatest 

health risk of all asbestos types and is the riskiest to miners 

and millers. 

3-2 
TABLE 3.1 

ANALYTICAL TECHNIQlJES FOR CONVENTIONAL AND INORGANIC POLLUTANTS IN SLUDGE 

I_ - 

Analytical Aqueous 

Preparation Technique QA/QC Detection 

Parameter Techniques (a) ( b ) Limit (mg/l) Comments Method 

Phos- Acidic Digestion C B 0.001 - High iron concentration (1) 365.3 

phorous Turbid samples St can cause precipitation 

(Ortho & must be filtered SP and loss of phosphorous 

Total 1 after digestion - Turbidity interference 

- 24 hr-hol~mq time 

Total - Digestion solution 2 (1) 

Kjeldahl 

Nitrogen 

H2S04 digestion C B 0.05 times for sludge 351.2, 3 

St. - 24 hr-holding time 

- Fe t Cr catalyze; Cu 

inhibits reaction 

Ammonia Calorimetric C SP 0.05 

reaction ISE 

- Hg can complex with NH4 (1) 350.1 

- Filter sample 350.2, 3 

-.Distillation required (2) 417A, 

Prior to analvsis B. D. E. G 

Nitrate Reaction to C 0.1 - Dissolved organic (11 352.1 

brucine sulfate or matter (3) 9200 

Nitrate-nitrite N 

Nitrate- Hydrazine or C 0.05 - Filter sample for Cd (1) 353.1, 

Nitrite Cd reduction I - Strong oxidizing or 353.2 

or reducing agents 

- Suspended matter in 

reduction column 

- Samples which contain high 

cont. of metals or orqanics 

Nitrite Diazotization S 0.5 (1) 354.1 

121 419 
'J'ARLE 3 . 1 (Continued) 

Analytical Aqueous 

Preparation Technique QA/QC Detection 

Parameter Techniques (a) lb) Limit (my/l 1 Comments Method 

_- --__--_ ____ -.--- --.- -_ ..--- ,... -.-- 

Cyanide CN converted to c B 0.02 - Fatty acids and (1) 335.2 

HCN by reflux- St. sulfides interfere (3) 9010, 

dist.illation SP OK 90-2 

Phenolics Distillation and C B 0.002 - 24 hr-holding time (1) 42i.l 

extraction St - Sulphur compounds and (2) 5lOA 

SP oxidizing agents or C 

interfere (3) 9065, 

9066. 9Q67 

Tot-al Inorganic Catalytic B 1.0 - Carbonate + bicarbonate (I) 415.1 

Organic carbon combustion & St- interfere (2) 505A 

Carbon removal di ~pers ive IRS12 _..._,_, (3) 9060 

Chemical Oxidation t-o Tit-rat ion B 5.0 - Possible loss of (1) 410.1, 

Oxygen potassium dichro- St volatiles (Block 

Demand mate and HC 1 SPI - Chloride oxidation digestion) 

could be an (2) 1508 A 

interference or-E 

Bio- Incubation Measurement B 2.0 - 5-day incubator (1) 4K-lchemical of reduction St (2) 507 

Oxvsen2mand . --.--.A~- DO Sp 

Oil and Solver1t G B 5.0 (1) 413.1,2 

Grease extraction SP (2) 503A, D 

(3) 9070, 

or 9071 

pH Solution in ISE St -__- - Interference from solids(l) 150.1 

suspension with and oily residues (3) 9040 

fluid (4) p. 900, 

--- --- ---- -- -_-uzrf. 

CEC RaCl. /treat.ment: 

4 

T None cited in - Acid soils (3) 9080 

(aci exctianye) C references (4) Ibid. 

.f hrlseexc!ldmt'l-~ _..._. __________.__- 
TA6T.E 3.1 (Continued) 

ANALYTICAL TECHNIQUES FOR CONVENTIONAL AND INORGANIC POLLUTANTS IN SLUDGE 

.~. .__~._. 

Analytical Aqueous 

Preparation Technique QA/QC Detection 

Parameter Techniques (a) (b) r,imi t (mg/l ) Comments Method 

--.-. ~. ---. .~ 

CEC Na acetate Emission Otle B No data - Neutral, saline, or (3) 9081 

sludge sol'n, Ok per available calcareous soils (4) p. 891 

isopropanol absorption batch 

wash, NH4 AAS 

acetate @xc-e 

Solids Filtration Gravimetric B 4.0-10.0 (1) 160.1 

-- 5 

% Solids Evaporation Gravimetric B N/A 1;; i60.3 

- --.lu-d~ 

(1) 

(2) 

(3) 

(41 

(a) 

( 1:1 

Metltodg for memica Arlalvsis of Water and Wastes, EPA-600/4-79-020, March 1983. 

Standard Metl1od.s for the Exarrlirlio!) of Water and WasLew+ter, 16th Edition, Mary Ann 

Franson, managing ed. , American Public Health AFsociation, Washington, DC, 1985. 

Test Mews for Evalllat,-incl Soli&Wst.e_, Third Edition, (SW-8463, EPA, September 

1986. 

@'Methods of Soil Analysis", Agrollotny Monograph Number 9, C.A. Black, ed. , American 

Society of Agronomy, Madison, Wisconsin, 1965. 

C Calorimetric; DO - Dissolved Oxygen; G Gravimetric; IH - Infrared; ISE; - Ion 

Selective Electrode; S -. Speci_1-(.)I)l~o~olnel..ric: ; T - Titrat:ion 

B - Blank(s); St. - St.anclards; S1' - Spike(s) 
In certain cases, such as when large scale asbestos removal 

is/will occur during the permit term or in municipalities ;Ihere 

asbestos industries are located, the permit xriter or the 

permittee may feel that sampling the sewage sludge for asbestos 

is warranted. Consult Table 2.4 for the appropriate sample 

sizes, containers, preservatives and holding times. Unless 

sample preparation will be within 43 hours, the sample should be 

refrigerated or stored in the dark to prevent bacterial growth. 

Although there are tests which differentiate between the 

various asbestos types, current research does not associate 

health risk with specific types. The risk from asbestos is 

directly proportional to the concentration of airborne respirable 

particles. Thus current recommended analytical detection methods 

count fibers per area. Respirable particles are those with a 

diameter (length in this case) of less than 2 microns, which can 

only be detected using transmission electron microsropy (TS?!!!. 

The polarized light microscopy (PLM? method does not detect 

respirable particles. 

3.2 METALS 

There are several analytical techniques used for the 

determination of metals in sewage sludge, ulth variations in both 

the sample preparation and analysis steps. A discussion of these 

techniques follows. 

3.2.1 Analvte Isolation/Preparation Overvie?; 

Two approaches are currently used to evaluate the 

concentrations of metai contaminants in sludges. The most 

frequently used approach involves determination of the total 

metal content or other materials of interest, without retard to 

chemical form. The analyt ical techn iques for such determinat izns 

3-6 
are designed to solubilize all of the metal species (bound to 

organic particulates and mineralogicaily bound). In the other 

approach, often referred to as the "leachate approach," the 

proportion of the total contaminant loading which will become 

available or mobilized under environmental conditions is 

determined. Thus, leachate techniques are designed to mimic a 

given environmental scenario. With either approach, the 

complexity and variability of sludge matrices has made the 

development of Sample preparation techniques a great analytical 

challenge. 

The t;Jo primary steps for sample preparation of metals in 

sewage sludge are (1) dissolution of the sample portion 

containing the metal components of interest, and (2) elimination 

of inorganic and organic interferences. The preparation 

procedure must be capable of effectively liberating the analytes 

from. the solid constituents, solubilizing the elemental .sTecles, 

homogenizing the sample phase(s) of interest, as well as 

completely oxidizing the associated organlcs. Sludge matrices 

are challenging in this regard because of the high or.ganlc Ievois 

and solids leadings characteristics. 

All state-of-the-art sample preparation procedures for total 

metal determinations depend on ac id-mediated diges-,ions and 

#chemical or physical oxidation techniques. The approach involves 

the use of strong acid and elevated temperature digestion 

procedures in combination with chemical or physical oxidants. 

The modifications which have been used include variations in 

acids, oxidation reagents, physical oxidation techniques, 

reaction conditions, and/or the sequence in which components are 

employed. Acids used most frequently include nitric acid (HNO,), 

hydrofluoric acid (HF), hydrochloric acid (HCL), and perchloric 

acid (HCLC,! ; while hydrogen peroxide and perchloric acid are 

3-7 
common oxidizing reagents. High temperature (SSO'OC) combustion 

and low temperature plasma ashing (LTPA) have been used successfully as physical oxidants. Closed system digestion procedures 

are also used successfully. 

Two closely related techniques to estimate the amount of 

inorganic and organic contaminants which may be leached from the 

sludge after disposal in landfills or surface impoundments are 

the Extraction Procedure protocol and the Toxicity Characteristic 

Leachate Procedure. In both procedures the sludge is maintained 

in an aqueous siurry under a given set of conditions, after which 

contaminant levels are measured on the filtered aqueous media. 

The Extraction Procedure (EP) test developed by EPA (in response 

to RCRA legislation) to evaluate the impact of landfill waste 

disposal practices on subsurface and surface waters (40 CFR Part 

261 Appendix II) evaluates criteria fo-r 8 metals and 6 

pesticides. The proposed Toxicity Characteristic Leaching 

Procedure (TCLP) 51 Federal Reaister 21648 Is expected to be 

promulgated in August/September of 1989. The TCLP test which 

evaluates the same 8 metals and 6 pesticides and an additional 38 

compounds -dill replace the Z? Zest after promulgation. 

3.2.2 Analvtiral Technioues for Metals 

3.2.2.1 Sample Preparation/Digestion 

Table 3.2 shows the sample preparation/digestion :echnlqe 

recommended by the USEPA. Method 3050 (SW-846, 3rd ed.) is an 

acid digestion procedure used to prepare sediments, sludges, and 

soil samples for analysis by flame or furnace atomic absorption 

spectroscopy (FLAA and GF?&, respectively) or by inductively 

coupled argon plasma spectroscopy (ICAP). Sampies prepared by 

this method may be analyzed by ICAP for all the metlis listed 

below, or by FLAA or GFAA as indicated: 

3-8 
FLAA GF.AA 

Aluminum 

mtimony 

Barium 

Beryllium 

Cadmium 

Calcium 

Chromium 

Cobalt 

Copper 

Iron 

Lead 

Magnesium 

Manganese 

Nickel 

Potassium 

Silver 

Sodium 

Thallium 

Tin 

Vanadium 

Zinc 

Arsenic 

Beryllium 

Cadmium 

Chromium 

Cobalt 

Copper 

Iron 

Lead 

Manganese 

Nickel 

Selenium 

Silver 

Zinc 

Thallium 

Vanadium 

Method 3050 prepares samples for analysis of total metals 

(except mercury, silver and antimony1 determination through 

vigorous digestion in nitric acid and hydrogen peroxide followed 

by dilution with either nitric or hydrochloric acid. This method 

is not appropriate for mercury, silver, and antimony because of 

potential for volatilization. For the digestion and analysis 

procedures for mercury, silver and antimony, see section 3.2.2.2. 

3.2.2.2 Analytical Detection Methods 

Metals should be analyzed using either Atomic Absorption 

Spectrometry (AAS) or Inductively Coupled Argon Plasma (ICAP). 

The following discussion generally describes both methods. 

Inductively Coupled Argcn Plasma is a form of.optical 

emission spectroscopy which uses an argon plasma to excite ions 

and atoms. This process causes the ions and atoms to emit light 

which is measured as a signal. The signal response is 

proportional to concentration level, and each element emits a 

uniquely characteristic light. This technique poses several 

advantages. A linear relationship between concentration and 

signal response can be expected over 4-6 orders of magnitude. 

Detection limits are low (although not as low as AAS, and not 

strongly inhibited by matrix variation); costs are moderate since 

3-9 
TABLE 3.2. 

RECOMMENDED PREPARATION TECHNIQUE 

FOR ELEMENTAL ANALYSIS OF SLUDGE SAMPLES 

METHOD 3050"' 

1) Mix the sample thoroughly to achieve homogeneity. For each 

digestion procedure, weigh to the nearest 0.01 g and 

transfer to a conical beaker a l.OO- to 2.00-g portion of 

sample. 

2) Add 10 ml of 1:l HNO,, mix the slurry, and cover with a 

watch glass. Heat the sample to 95*C and reflruc for 10 to 

15 min without boiling. Allow the sample to cool, add 5 ml 

of concentrated HNO,, replace the watch glass, and reflux 

for 30 min. Repeat this last step to ensure complete 

oxidation. Using a ribbed watch glass, allow the solution 

to evaporate to 5 ml without boiling, while maintaining a 

layer of solution over the bottom of the beaker. 

3) After Step 2 has been completed and the sample has cocled, 

add 2 ml of Type II water and 3 ml of 30% H,Qi. Cover the 

beaker with a watch glass and return the covered beaker to 

the hot plate for warming and to start the peroxide 

reaction. Care must be taken to ensure that losses do not 

occur due to excessively vigorous effervescence. Heat until 

effervescence subsides and cool the beaker. 

4) Continue to add 30% H,O, in l-ml aliquots while warming 

until the effervescence is minimal or until the general 

sample appearance is unchanged. 

NOTE : Do not add more than a total of 10 ml 30% HiCz. 

(1) USEPA "TEST METHODS FOR EVALUATING SOLID WASTE: VOLUME 1A" 

SW-846 3rd EDITION, NOVEMBER 1986. CHAPTER 3, PP. 3050-1,5. 

3-10 
many elements may be determined at once; and anaiysis time is 

fairly rapid. The primary drawbacks are: matrix interferences 

(as with all analyses); the fact that soiid samples cannot be 

analyzed directly as in AAS; and the high cost of purchasing ICAP 

instruments (more than $100,000). 

The basic principle behind atomic absorption spectroscopy is 

the opposite of the emission method, ICAP. In AAS, the analyze 

(metal) is dissociated into atoms in a flame or furnace, and 

passed through a light beam from the reference source. This 

reference source emits a beam of the characteristic atomic 

spectrum of the analyte. The analyte in the sample ~-ill absorb 

this energy thus decreasing the original signal to the detector 

from the reference beam. Since absorption is directly 

proportional to concentration, the analyte concentration can be 

determined. Selection of a specific wavelength which corresponds 

to one of the more intense characteristic line of the analyte's 

spectra allok;s for high eiement specificity. For this reason, 

AAS is more responsive than IGAP to lower concentrations of 

metals in sludge. However, this very precise nature of .VLS Is 

also the cause of its major drawback: cnly cne elemental 

determination per sample is possible at a time. Thus, cAhe total 

analysis time of AAS is significantly greater than that of ICA? 

when many metals are present in the sample. 

Fn sewage sludge applications, it is important to reailzo 

that both of these analytical techniques are reliable tools and 

neither offers a significant technical advantage over the other. 

However, ICAP's capability to simultaneously analyze multiple 

elements is a tremendous advantage in terns of sample throughput 

and labor savings, which may outweigh the noted limitations.- For 

sludge applications, EPA recommends either method and leaves the 

3-11 
final decision to individual POTWs. Table 3.3 s;lmmarizes the 

relative advantages and disadvantages of ICAP and .AAS. 

TABLE 3.3 

COMPARISON S~X?G'RY OF ICAP ?JJQ AAS 

ICAP AA.5 

Cost for Instrument 

Cost per Sample 

Detection Limits 

Precision 

Linear Working Range 

Sensitivity 

Number of Elements/Sample 

Analysis Time 

Spectral Interference 

Matrix Interference 

+ 

L 

i 

f + 

t Lb 

c 

L 

- disadvantage 

+ advantage 

++ extra advantage 

EPA recommends Nethod 60i0 for the deternination of net,a-ls 

in solution by Inductively Ccupled Argon Plasma atomic emissisr. 

spectroscopy (ICAP). This method can be found in the CTSEP?, 

manual "Test Methods for Evaluating Solid Na.sc,e," (S'W-246 , >;c-r. 

1986, 3rd Ed., Vol lA, 9~. 601O-1,171. 2.e mezkod is a23plicable 

to a large number of metals and wastes. All matrkes , including 

ground ;Jater, aqueous samples, EP extracts, industrial .tiastes, 

soils, sludges, sediments, and ot:?er solld.wastes, require 

digestion prior to analysis. EPA recommends digestion yethod 

30.50 (57-846, 3rd Ed. - see Section 3.2.2-l). 

3-12 
Elements for which Kethod 6010 is applicable are listed in 

Table 3.4. Detection limits, sensitivity, and optimum ranges of 

the metals will vary *dith the matrices and model of spectrometer. 

The data shown in Table 3.4 provide concentration ranges for 

clean (interference-free) aqueous samples. Due to matrix 

interferences, the detection limits in typical sludge sampies 

will be somewhat higher. Use of this method is restricted to 

spectroscopists ;iho are knowledgeable in the correction cf 

spectral, chemical, and physicai interferences. 

Atomic ?&sorption Methods 

EPA recommends use of the methods listed in the manual "Test 

Methods for Evaluating Solid Kaste" (W-846, Nov. 1986, 3rd Ed., 

Vol 1A) for the determination of metals in solution by atomic 

absorption spectroscopy. A complete set of procedures for each 

metal-specific method may be found on pages 7000-L to 7950-3. 

These methods are simple, rapid, and applicable to a large number 

cf metals in drinking, surface, and saline 'daters as '.4ell as 

domestic and industrial wastes. Ground *;ater, aqueous samples 

other than drinking vater, EP extracts, industrial wastes, soils, 

sludges, sediments, and other ~'astes require digestion prior tc 

analysis. EPA r ecommends digestion Nethod 3050 (.5X-846, 3r2 Ed. 

- see section 3.2.2.1). 

Detection limits, sensitivity, and optimum ranges cf t:?e 

metals will vary vitih the matrix es and models of atomic 

absorption spectrometers. The data shown in Table 3.5 provide 

some indication of the detection limits obtainable by direct 

aspiration and by furnace techniques. Due to the matrix 

' For drinking crater and other non-sludge appiications, priority 

pollutant scans may require very low contaminant detection 

levels. Therefore, there may be no choice except t3 rely cn the 

lower detection limit Capability of graphite furnace .VCG. This, 

in turn, t;ill determine-the digestion method used. 

3-13 
TABLE 3.4 

RECOMMENDED INDUCTIVELY COUPLED WAVELENGTHS 

AND ESTIMATED INSTRUMENTAL DETECTION LIMITS 

Wavelength3 

(ml) 

Wastewater ZMSL's Best E?J?SL?s 

Estimated SLUDGE Estimate of 

Detection Detection Routine 

Limitb Limit' SLUDGE Limit 

tug/L) (ug,/L) fug/L) 

Element 

Aluminum 308.215 

Antimony 206.833 

Arsenic 193.696 

Barium 455.403 

Beryllium 313.042 

Boron 249.773 

Cadmium 226.502 

Calcium 317.933 

Chromium 267.716 

Cobalt 228.616 

Copper 324.754 

Iron 2'59.940 

Lead 220.353 

Magnesium 279.079 

Manganese 257.610 

Molybdenum 202.030 

Nickel 231.604 

Potassium 766 .491 

45 

32 

53 

2 

0.3 

5 

4 

10 

6 5 1 I) 

7 

42 

30 

2 

8 

15 

See note d 

-- -- 

-- 

-- 

-- 

1 

-- 

-- 

S 

20 50 

10 

-- 
TABLE 3.4 (cont.) 

RECOMMENDED INDUCTIVELY COUPLED ~JXVELENGTHS 

AND ESTIMATED INSTRUMENTAL DETECTION LIMITS 

Element 

Wastewater EMSL's Best ZMSL'S 

Wavelengtha Estimated SLUDGE Estimate of 

(I-lttl) Detection Detection Routine 

Limit" Limit' SLUDGE Limit 

(ug/L) fug/L) fug/L) 

Selenium 196.026 75 75 100 

Silicon 288.158 58 

Silver 328.068 7 -- -- 

Sodium 588.995 29 -- -- 

Thallium 190.864 

Vanadium 292.402 

100 

-- 

150 

-- 

Zinc 213.856 2 5 15 

Reference: Test Methods for Evaluating Sclid Waste: .5X-846. 

a The wavelengths listed are recommended because of their 

sensitivity and overall acceptance. Cther vavelengt:hs may be 

substituted if they can provide the needed sensizivlty and are 

treated ;Jith the same corrective techni,ques for spectral 

interference. In time, other elements may be added as more 

information Becomes available and as required. 

b 

C EPA's Environmental Monitoring Support Laboratory detection 

limit ranges. 

d Highly dependent on operating conditions and plasma position. 

The estimated instrumental detection iimits are shown. Thev _ are 

given as a guide for an instrumental limit. The ac+Lla' c - method 

detection limits are sample dependent and may vary as t!le sample 

matrix varies. 
TABLE 3.5 

ATOMIC ABSORPTION FLAME AND FTJRKXCD, INSTRUMENTAL DETECTION 

AN-D SENSITIVITY LIMITS FOR WGTZ'ISATER SAKPLES 

Metal 

Direct Aspiration Furnace Procedure'.' 

Detection Limit Sensitivity Detection Limit 

(mg/L) (mg;L) tug/L) 

Aluminum 0.1 1 -- 

Arsenic Antimony 

0.2 0.5 3 

0.002 -- 1 Barium(p) 0.1 0.4 -- 

Beryllium 0.005 0.025 0.2 

Cadmium 0.005 0.025 0.1 Calcium 0.01 0.08 -- 

Chromium 0.05 0.25 1 

Cobalt 0.05 0.2 1 

copper 0.02 0.1 -- 

Iron 0.03 0.12 -- 

Lead 0.1 0.5 1 Magnesium 0.001 0.007 -- 

ManganeSe 0.01 0.05 -- 

Mercury' 0.0002 -- -- 

Molybdenumfp) 0.1 0.4 1 Nickel(p) 0.04 0.15 -- 

Potassium 0.01 0.04 -- 

Selenium' 0.002 -- 2 Silver 0.01 0.06 -- 

Sodium 0.002 0.015 -- 

Thalli*um 0.1 0.5 1 

Tin 0.8 4-- 

Vanadium(p) 0 .2 0.8 4 

Zinc 0.005 0.02-- 

- . 

Reference: Test !qethods for Evaluating Solid Xaste: sx-846. 

NOTE: The symbol (pj indicates the use of pyrolytic graphite 

tJith the furnace procedure. 

a F or furnace sensitivity values, consult instr-.xnent cperating 

manual. 

b Gaseous hydride method. 

C The listed furnace values are those expected xher, using a 

20-u-L injection and normal gas flow, except in the cases cf 

arsenic and selenium, where gas interrupt is used. 

d Cold vapor technique. 
interferences, the detection limits for typical sludge samples 

will be somewhat higher. 

Mercurv Analvsis 

The physical-chemical characteristics of mercury are not 

amenable to digestion by the generally recommended technique, 

Method 3050. For the determination of total mercury (organic and 

inorganic) in soiis, sediments, bottom deposits, and sludge 

material, EPA reccmmends using Method 7471, a cold-vapor atomic 

absorption spectrcmetry. This method appears in the EPA manual 

"Test Methods for Evaluating Solid TWaste." (SW-846, Nov. 1986, 

3rd Ed., pp. 7471-1,101. Prior to analysis, the solid or 

semi-solid samples must be prepared according to the procedures 

discussed in this method. The typical detection limit for this 

method is 0.0002 mg/L. 

Antimony and Silver .Analvsis 

The procedures for preparation of antimony and silver 

samples are given in Method 3005. Wethod 3005, a soft digestion, 

is presently the only digest: 'on procedure recommended for 

antimony. It yields better r ecoveries than either Method 3020 or 

3050. There is no hard digestion for antimony at this time 

(SW-846, Nov. 1986, 3rd Ed., p, 7041-2). Samples prepared by 

Method 3005 are amenable to determination by either IChp Method 

6010 or the atomic absorption furnace technique, l!ethod 7045. 

(SW-846, 3rd Ed. - see pp 7041-l through 7041-41. Detection 

limits for Method 7041 are 3 ug/L for antimony and 10 mg/l for 

silver. 

3-17 
3.3 ORGANICS 

The evolution of analytical techniques for organic 

contaminants has involved a number of modifications to a basic 

method in order to widen potential applications. Because the 

instrumentation is complex and the number of possible analytes is 

large, quality control is difficult to monitor and several 

analytical techniques are required. As with analyses for metals 

and other elements, the organic-rich ccmplex matrices characteristic of sewage sludges often mean that analyte 

extraction/isolation procedures play a significant role in the 

reliability of the resultant analytical data. 

3.3.1 Overview of Analvte Extraction and Isolation 

For a number of reasons, EPA has focused regulatory 

attention on two categories of contaminants: volatile organics 

and semi-volatile organics. 'While the classification of these 

groups is founded upon inherent physical/chemical properties, 

extraction and isolation techniques are the functional basis for 

the distinction. 

Volatile Oroanics 

Two methods are available for extraction and isolation cf 

volatile organics in aqueous and solid matrices: headspace 

techniques and purge and trap techniques. Several versions of 

these procedures have been sanctioned by regulatory agencies 

and/or developed for use in specific applications. For POTW 

sludge sampling and analysis, EPA recommends t-do analytical 

methods (:624C, 624-S! which both extract via purge and trap (see 

Section 3.3.2). 

3-18 
Purge and trap requires moderate sample preparation. The 

method relies upon a stripping process in which an inert gas is 

bubbled through the sample to remove the volatile organics. The 

volatilized organics are transferred from the aqueous/solid phase 

to the gaseous phase and subsequently trapped on a solid 

adsorbent column. The adsorbent column is then heated and the 

trapped organics are thermally desorbed and swept into the 

analytical instrument. 

Semi-volatile Organics 

The first Step in all procedures for determination of semivolatile organics is solvent extraction. (Note: For extraction 

procedures recommended by EPA for sludge analysis see Section 

3.3.2). The sample material is mixed and agitated with a 

solvent, causing the organic analytes to be preferentially 

partitioned into the solvent phase. Extractions are typically 

performed at both acidic and basic pH ranges to facilitate 

extraction of ionizable organics. Modifications to the 

extraction method are usually based upon the manner in which the 

sample-solvent mixture is agitated and post-extraction cleanup 

procedures. 

The organic solvent used most frequently for extraction of 

semi-volatile analytes is methylone chloride, either singly or in 

combination with a more polar solvent. Extraction techniques 

which are applicable to sludge and solid matrices include: 

0 Sonication extraction 

0 Continuous liquid-liquid extractors 

0 Soxhlet extraction 

0 Mechanical agitation (shaker table, homogenization, or 

wrist-action shaker). 

3-19 
Sonication relies on the mechanical energy developed from 

ultra-sonic devices to affect agitation and solvent-solid 

contact. The best approach involves the use of a sonication horn 

which is immersed into the solvent-sample mixture, rather than a 

sonication bath. This technique has also been proven effective 

in sludge and sediment applications. 

Continuous liquid-liquid extractors and Soxh:et extractors 

employ the same basic principle of operation. The extraction 

solvent is distilled from a reservoir, condensed above the sample 

material, and subsequently. rains down through the sample. The 

distillation-condensation process continues until a volume of 

solvent has collected sufficient force to establish a siphon, at 

which point the extraction solvent is siphoned back into the 

reservoir. The cycle is repeated with freshly distilled solvent 

and is generally allowed to occur for 12-24 hours. The 

continuous liquid-liquid extraction procedure can only be used on 

low solids 1<5%) sludges, while the Soxhlet technique is most 

useful for materials with low water content. 

A variety of mechanical agitation techniques have been llsed 

for extractable organics determinations, including hcmogenization, wrist-action shakers and platform shakers (shaker 

tables). The objective of each technique is to maximize the 

contact between the extraction solvent and. the solid partlclcs. 

Wrist-action and platform shakers have both proven adequate, with 

wrist-action shakers generally preferable for smaller sample 

containers and platform shakers preferable for larger extracticn 

vessels. Homogenization relies on agitation of the solvent-solid 

mixture, rather than agitation of the entire extraction vessel. 

This technique has been used quite successfully in sludge 

applications as a result of its supericr agitation. Zowever, 

3-20 
sand, a fairly common constituent of sewage sludge, literally 

chews up high speed homogenizers. 

As a result of the complexity of sludge matrices, 

fractionation and/or cleanup procedures are often required after 

sample extraction to minimize interference. The basic concept 

used in virtually all cleanup techniques is selective adsorption 

of the interfering components. Although a variety of cleanup 

procedures have been developed for specific analytes, the 

techniques commonly employed for the listed applications include: 

0 

0 

Cleanup procedures can be used FndivLdLally or in combination 

Gel permeation resins - broad spectrum cleanup and 

higher molecular weight biogenic organics 

Activated carbon - fractionation and general purpose 

cleanup 

Alumina adsorbent - inorganic adsorbent 

Florisil adsorbent - inorganic adsorbent 

Silica gel adsorbent - inorganic adsorbent 

Copper and mercury - removal cf sulfur-containing 

compounds. 

with other procedures, depending upon the need of the particular 

application and the complexity of the sample. 

For more detail regarding extraction and isolation 

techniques, consult the references cited in 40 CFR Part 136, 

"Guidelines for Establishing Test i'rocedures for the Analysis of 

Pollutants." 

3-21 
3.3.2 Recommended Analytical Techniaues for Orsanics 

For determining concentrations of organic pollutants in 

sludge, EPA recommends two methods designed for qualitative and 

quantitative analysis of municipal and industrial wastewater 

treatment sludges: 

0 Volatile Organics - 624-S (EPA 1984b) or 1624C (EPA 

1988a) 

0 Semi-Volatile Organics - 625-S (EPA 1984b3 or 1625C (SPA 

1988a) 

Each of these two methods employ gas chromatography/mass 

spectrometry (GC/MS). 

GC/MS is a combination of tW0 microanalytical techniques: 

gas chromatography (a separation tec.hnique) and mass spectrometry 

(an identification technique). h sample allquot is prepared for 

extraction, extracted, then introduced to the GC/?lS system. The 

extract is vaporized quickly at an elevated temperature and 

carried by an inert gas (mobile phase) througih a coated coLumn 

(stationary phase). Separation of the extract components Is 

effected by their differential partitioning bet-Geen s-,ationary 

and mobile phases. The separated components exit the column and 

enter the mass spectrometer (MS) rc;here they are decomposed to 

specific unimolecular species. The manner in 7hic.i a component 

fragments is rharacteristic af that component and is -,he basis 

for identification. The MS detector quantifies a compound by 

responding with a signal prDportiona1 to the detected amount of 

the compound. 

The GC/MS system is calibrated by measuring signal response 

to three to five analyte standard solutions of various 

concentrations (e.g., 29-160 ng;/ml). The solutions are carefully 

3-22 
prepared mixtures of pollutants suspected to be present in the 

sample, as well as a few labeled pollutant analogs known as 

internal standards. The accumulated measurements form an 

instrument response curve. Samples are spiked with the same 

internal standards at a fixed ccncentration immediately prior to 

analysis. If the MS detects any sample-originated pollutants, 

the generated signal for each pollutant is measured against both 

the internal standard and the response curve. 

GC/MS analysis affords several advantages over other 

techniques: 

0 Provides qualitative and quantitative information about 

a wide range of organic compounds. 

0 Confirms specific information from a small sample size. 

0 Produces a spectrum with a fragmentation pattern, or 

fingerprint, which can be used to identify an unknown. 

3.3.2.1 Methods 1624C and 1625C 

Methods 1624C and 1625C are draft methods for analyzing 

volatile organics (Method 1624C) and base/neutral, non and semivolatile organics (Method 1625C) in sludge. These methods were 

developed by the USEPA Office of Water Industrial Technology 

Division, and are derived from previous methods 1624 and 1625 

(see 40 CFR Part 136) for analyzing wastewaters. 

The 1624C/1625C (and 1624/1625! test procedures are isotope 

dilution techniques. In conventional GC/MS, up to six internal 

standards are used to quantify the response of perhaps several 

dozen analytes. Isotope diluticn GC/MS employs stable, 

isotopicall y labeled analogs of the compounds of interest, which 

is analogous to providing a separate internal standard for each 

analyte. The result is that isotope dilution GC/MS is sensitive 

3-23 
to even minute contaminant concentrations. Methods 1624C/1625C 

and 1624/1625 are similar in this respect but differ in sample 

preparation. 

Method 1624C sample preparation for sludge samples consists 

of the following three routes, depending on the percent (%I 

solids content of the sludge. If the solids content is less than 

one percent, stable isotopically labeled analogs of the compounds 

of interest are added to a 5 gram sample and the sample is purged 

in a chamber designed for soil or water samples. If the solids 

content is 30 percent or less, the sample is diluted to one 

percent solids with reagent water, and labeled compounds are 

added to a 5 gram aliquot of the sludge/water mixture. The 

mixture is then purged. If the solids content is greater than 30 

percent, five ml of reagent water and the labeled compounds are 

added to a 5 gram aliquot of sample. The mixture is then purged. 

Method 1625~ sample preparation for sludge.samples consists 

of the following three routes, depending on. the percent (%I 

solids content of the sludge. If the solids content is less than 

one percent, a one liter sample is extracted with methylene 

chloride using continuous extraction techniques. If the solids 

content is 30 percent or less, the sample is diluted to one 

percent solids rjith reagent water, homogenized ultrasonically, 

and extracted. If the solids content is greater than 30 percent, 

the sample is extracted using ultrasonic techniques. Each 

extract is subjected to a gel permeation chromatography (C-X) 

cleanup. 

These methods are currently undergoing revision at EPA's 

Environmental Monitoring and Support Laboratory for problems 

relating to the sample preparation portions. They are the 

3-24 
methods used in the National Sewage Sludge Survey (which EPA is 

conducting to provide a current data base to be used to set 

pollutant limits, evaluate risks of use and disposal practices, 

and evaluate the impacts of the proposed rule) and also are 

discussed in the 40 CFR Part 503 regulation proposed on February 

6, 1989 and now out for comment. Depending on the results of the 

comment period, the isotope dilution methods may be exclusively 

required for priority pollutant organics analysis when 40 CFR 

Part 503 is finalized. 

3.3.2.2 Methods 624-S and 625-S 

Methods 624-S and 625-S are existing methods for the 

measurement of organic priority pollutants in sludges. These 

test procedures were derived from previously developed methods 

624 and 625 for analyzing wastewaters (see 40 CFR Part 136). The 

624-S/625-S techniques are conventional GC/MS and operate as 

described Lz Section 3.3.2. Method 624-S is used to analyze for 

volatile organic compounds. Method 625-S is used for 

semi-volatile or nonvolatile organics. 

In Method 624-S, an inert gas is bubbled through. a 10-z-L 

sludge aiiauot contained in a purging chamber at ambient 

temperature. The purgeable compounds are transferred from the 

aqueous phase to the vapor phase. The vapor is carried through a 

sorbent col.umn where the purgeables are trapped. After purging 

is completed, the sorbent column is heated and backflushed vith 

the inert gas to desorb the purgeables into a gas chromatographic 

column. The gas chromatograph is temperature programmed to 

separate the purgeables which are then detected with a mass 

spectrometer. 

Method 625-S uses repetitive solvent extraction (see section 

3.3.1 ) aided by a high-speed homogenizer. The extract is 

3-25 
separated by centrifugation and removed with a pipette or 

syringe. Extracts containing base/neutral compounds are cleaned 

by silica gel or florisil chromatography or by gel permeation 

chromatography (GPC). Extracts containing the acidic compounds 

are cleaned by GPC. The organic priority pollutants are 

determined in the cleaned extracts by capillary column or packed 

column GC/MS. Option A, i.e., extract cleanup by silica gel cr 

florisil chromatography and analysis by capillary column K/MS 

IHRGC/MS) is preferred since HRGC/MS allows easier data 

interpretation. 

While Methods 1624C/162SC provide lower detection limits, in 

some cases, than Methods 624-S/625-S, these methods are also more 

costly. Presently, Methods 1624C/1625C cost about $2,200-$2,400 

per sample, which is approximately $200-$400 more than a similar 

analysis by Methods 624-S/625-S. The extra cost reflects the 

Method 1634/1635 isotope spikes and approximately two weeks cf 

zor!c necessary to prepare additional spectra; libraries. 

Neither Methods 624-.5/625-S or Methods 1624Ci1625C detect 

pesticides at very low concentrations. Xithcut megabcre c2 1,a-m 

analysis, which may cost an additional $1,900, none of Liese 

methods ziil do better than the detection limits, 20-50 ppb. "or 

some highly mixed pesticides such as chlordaze, these methods ran 

only rJ,ersect ZOO-300 ppb. At this time, EfA is not.reccmmendlrg 

megabore column pesticide analysis naticnzlly. However, in 

situations where lower detecticn :ixTllts are crucial such as In 

PCB or pesticide analysis, megaboie column analysis is necessary. 

3.4 P?VTHOGENIC KCROORGAXISMS 

A pathogen or pathogenic agent is an‘; blologlcal species 

t:iat can cause dicease in the host organism !primarily humans). 

These organisms fall into four bread categories: viruses, 

3-26 
bacteria, parasites, and fungi. From these categories, species 

commonly found in sewage sludge include fecal coliforms, fecal 

streptococci, salmonella, and ascaris (helminth). Wastewater 

sludge disinfection, the destruction or inactivation of 

pathogenic organisms in the sludge, is carried out to minimize 

public health concerns regarding these and other microbial 

agents. 

The 40 CFR Part 257 regulations issued under joint authority 

of Subtitle D of the Resource Conservation and Recovery Act 

(RCRA) and Section 405(d) of the Clean Water Act establish 

requirements for the disposal of solid waste which include 

pathogens in sewage sludge. The regulations (40 CFR Part 

257.3-6) require that sewage sludges applied to the land surface 

or incorporated into the soil be treated by a Process to 

Significantly Reduce Pathogens (PSRP). Public access must be 

controlled for at least twelve months after sludge applications 

and grazing by animals whose products are consumed Sy humans must 

be prevented for at least one month after application. Treatment 

by a Process to Further Reduce Pathogens IPFRP) is required for 

sewage sludge applied to the land surface or incorporated into 

the soil if crops for direct human consumption are grown within 

eighteen months after application, if the edible portion of the 

crop will touch the sludge. 

Rather than requiring a specific reduction or concentration 

for given pathogens, the process-based regulation (see Appendix 

II of 40.CFR Part 257) describes and sets numerical requirements 

for unit processes and operating conditions that qualify as PSRP 

and PFRP (e.g., criteria for process time and temperature and for 

volatile solids reduction). Thus permit compiiance is based on 

meeting process requirements, not pathogen reduction per se. 

Appendix II of 40 CFR Part 257 allows methods or operating 

3-27 
conditions other than those listed under PSRP or PFRP if 

pathogens and vector attraction are reduced commensurate vith the 

reductions attainable from listed methods. Appendix II (of 40 

CFR Part 257) does not prescribe the operation mode (i.e., batch 

or continuous) for digesters. The regulation also does not 

specify a method for calculating volatile solids reduction. Fcr 

a comprehensive discussion of the ways that volatile solids 

reduction may be calculated and their Iimitations, refer to 

Appendix B of this guidance document. 

Although the 40 CFR Part 257 regulations are based on 

specific processes rather than on meeting specific pathogen 

reduction levels, the regulations do provide that other processes 

"may be acceptable if pathogens are reduced to an extent 

equivalent to the listed processes.Tt In order to provide 

guidance on the equivalence of these other methods EPA has a 

panel of experts, the Pathogen Equivalency Committee (TEC), which 

evaluates the acceptability of the process based on the level of 

pathogen reduction, as determined by standardized analytical 

tests. For more comprehensive information on pathogen and 

guidance on whether alternative processes provide equivalent 

levels of pathogen reduction consult the draft "Guidance for 

Controlling Pathogens in Municipal Wastewater Sludge" PEC/EPA Yay 

1989 (to be finalized July/August 19891. 

Sampling techniques for determining pathogens in sewage 

sludge are no different than for other tests except that no 

preservatives are used. In the absence cf definitive sludge 

methods for determining bacteria concentrations, modified 

standard wastewater methods are often utilized. The analYytir,al 

methods for analysis of pathogens and indicator organisms are 

provided in Table 3.6. Unfortunately no standardized rethods 

exist for parasitic determinations. 

3-28 
1’ABLE 3.6 

~ALyTTCAI, TECtJNIQI.lE:S b’C)R DE’I’ERMTNATION OF PATHOGENTC MICROORGANISMS IN SEWAGE SLUDGE 

_- -- --- .-_.-_.- ..- -____- --..- 

Pathoge11 Preparation Technique Culture Media Reference 

___ -_--. 

Fecal Colifo m --- A(908 or 909) 

enter 

E. COli 

Salmone 

cocci. --- A( 91OA 

Centrifugatioli and filtration M-PC broth membrane h(912E 

filters 

la sp. E’i ltr’at ion Br i 11 i ant green-xylose A( 9I%C 

lysine desoxycholate agars 

or B 

1) or C: 

I 

Animal Vi ruses Centrifuyation, el.utriation, Tissue cl1 1 ture D 

f i It-ration, and flocculation 

Hclminth Ova Filtration --- A(91.7) or E 

Protozoa Fi 11,1’at. ion --- 

. .._ ---___ -.-- --lGLU.1- or E 

A) APIIA-AWWA-WPCF St-.andarc.l Methods ftsi--.t-lle Fxami rlat iorl of .Hater and Wast.ewat.er . 1.6th Ed. 

B) Slantely, I,. W. and Bart ley , auNrlmtu?rs of enterococci in water, sewage, and feces 

determined by the membrane filter technique with an improved mediumll, J. Bacteriology 

74: 591-595 (1957). 

D 1 41Ttle Manual of Methods J.or Vi rolo~~y” , EPA/GOti/4--84/o] 3 (February 1984) as revised. 

E ) FOX, J.C., Fitzr~erald, arlrl Lue-11 i 11(-j , “:<ewdye Ill.cjallisms: A Color Atlas”, Lewis 

Publ,ishers, Chelsea, Mic:llicjdn (1981 ) . 
The effectiveness of many PSRPs and PFRPs for reducing 

pathogens can be estimated by measuring the effects on fecal 

indicator organism densities (e.g., fecal coliform and/or fecal 

streptococcus). These tests are less expensive and easier to r 

than tests for specific pathogens and also provide good control 

data. 

li 

3-30 
4. QUALITY ASSURANCE/QUALITY CONTROL 

An essential part of a sampling and analysis program 

includes a well designed quality assurance/quality control 

(QA/QC) program. The extent of the QA/QC program should mirror 

the intent and purpose of the sampling effort. It should be 

noted that the facility is ultimately responsible for the quality 

of the data even if a contractor is used. Therefore, it behooves 

the POTW to have a good QA/QC program. 

If the purpose of the sampling and analysis program is to 

determine compliance with permit conditions, or to provide 

critical data for making a major cost decision, then the QA/QC 

program should be extensive and be able to demonstrate the 

precision, accuracy, representativeness, comparability and 

completeness of the data. The determination of these QA/QC 

parameters and their definitions are as follows: 

• QA is an overall program which guarantees the quality 

of the product. It includes a QC auditing process to 

prevent future defects. QA is synonymous with process 

control, continuous improvement and prevention of poor 

quality. QC is the examination of the product to 

determine ii it meets the specifications of the QA 

program. QC is part of the overall QA program. QC is 

synonymous with appraisal after the fact. An example 

of QC is that lab duplicate results must be within a 

certain percentage of each other or else the whole 

batch must be redone. 

• Laboratory QA includes prevention of data contamination 

during laboratory procedures. Contamination may be due 

to various other tests that are run in the lab at any 

given time. In order to assure that any sample 

contamination that does occur does not contaminate lab 

data, a lab QA sample, usually a deionized water 

"blank (or other "clean" appropriate material), is run 

along with the actual field samples. Lab QA also 

includes doing duplicates and spikes of the actual 

samples. Field QA serves the same purpose, to prevent 

data from being erroneous. However, it is virtually 

4-1 
• 

• 

• 

• 

impossible to prevent contamination of the samples 

since the sampling environment is not controllable. 

Therefore, the field blanks are subject to the same 

conditions as the samples, i.e., the containers are 

exposed to the environment as long as the sample 

containers are open, the sample and field "blank" are 

transported together. 

Accuracy, which is closeness to actual values, of all 

sample testing and analyses should be evaluated at a 

minimum frequency of 5 percent of the samples tested 

(i.e., at least one in every 20 Samples), using spiked 

samples. Accuracy is calculated from the known and 

analytically derived values of spiked parameters, and 

expressed as percent recovery. The accuracy required 

in the quality assurance program for the analyses is 

specified in each of the EPA methods (e.g., EPA 600 or 

1600 Series or EPA Methods for Chemical Analysis of 

Water and Wastes). 

Precision, which is repeatability of results, of sample 

analyses should be evaluated at a minimum frequency of 

5 percent (i.e., at least one in every 20 samples), 

using spiked samples in duplicate. Precision is 

calculated from the analytical results of the. spiked 

analytes in each set of duplicate samples., and 

expressed as percent relative standard deviation. The 

precision required in the quality assurance program for 

the analyses is specified in each of the EPA Methods 

(e.g., EPA 600 or 1600 series or EPA Methods for 

Chemical Analysis of Water and Wastes). 

Completeness is calculated as the ratio of valid 

measurements obtained to the number of valid 

measurements needed to reach a predefined statistical 

level of confidence in the resulting data. 

Completeness is determined and evaluated on the basis 

of data sets for each specific measurement process. 

Data are considered to be valid if both the accuracy 

and precision of the measurements meet the data quality 

objective (i.e., accuracy, precision, and compliance 

with analysis method protocol). 

All sampling should be performed using methods, 

procedures, and controls that ensure the collection of 

representative samples which thus ensures that the 

analytical results are representative of the media and 

the conditions being measured. 

4-2 
0 Comparability is a more qualitative QA measurement. 

All analytical data must be calculated and reported in 

units consistent with those specified in the applicable 

permit. Previously developed data generated for each 

facility abcut to be inspected is reviewed to ensure 

that no difficulties of data comparability will be 

encountered by following the specifications of the 

permit. If no previous data exist and the permit 

requirements are incomplete or ambiguous, data should 

be reported in the standard units prescribed in the 

appropriate EPA Methods (e.g., EPA 600 or 1600 series 

or EPA Methods for Chemical Analvsis of Water and 

Wastes). 

These QA/QC procedures are necessary for ensuring data quality. 

On the other hand, if the purpose of the sampling effort is to 

monitor plant performance for routine operation and maintenance 

(O&M) decisions, a simplified QA program that includes sample 

replicates and a field blank might suffice. 

Sludge sampling and analysis programs for determining 

compliance with permit conditions should include a written QA 

Plan. EPA guidance for the development of a QA Program (EPA 

Quality Assurance Project Plans (QAPP), 1983) identifies 16 

elements which should be addressed in a QA plan: 

Title Page 

Table of Cont ents 

Project Description 

Project Organization and Responsibility 

QA Objectives for Measurement Data in Terms of Precision, 

Accuracy, Completeness, Representativeness, and 

Comparability 

Sampling Procedures and Frequency 

Sample Custody 

Calibration Procedures and Frequency 

4-3 
Analytical Procedures 

Data Reduction, Validation and Reporting 

Internal Quality Control Checks 

Performance and System Audits 

Preventive Maintenance 

Specific Routine Procedures Used to Assess Data Precision, 

Accuracy and Completeness 

Corrective Action 

Quality Assurance Reports to Management 

In preparing a QAPP, the QA parameters and specifications of 

the analytical program should be dictated by the analytical 

parameters. The QA parameters are specified in each analytical 

protocol. There are situations (particularly for enforcement 

actions) in which more stringent protocols will be desired. 

In preparing the QA plans, the collection of field blanks 

(blanks to reflect sample handling effects) and sample replicates 

should be addressed. At a minimum, field blanks should be 

collected every day that sampiing is performed. Fieid blanks 

should be prepared at the beginning of each sampling event, at 

7 ' each discrete sampling site, by pouring American Society for 

Testing and Materials (ASTM) Type II reagent-uater'into prepared 

sample bottles. These sample bottles are randomly selected from 

the supply of prepared sample bottles; a sample container should 

be selected that is appropriate for each type of analysis for 

which environmental samples are being collected (see Table 2.:). 

The field blanks should be handled and analyzed in the same 

manner as environmental samples. Because field blanks and 

environmental samples are collected under the same conditions, 

field blanks analyses should be used to indicate the presence cf 

4-4 
external contaminants that may have been introduced into samples 

during collection. 

One f' leld replicate for every 20 samples or less should be 

collected at a preselected POTW monitoring point. Field 

replicates should be collected at the same time and in the same 

manner as the other environmental samples. Results of the field 

replicate analyses should be used primarily to assess the 

precision of the field sampling methods. 

In preparing and evaluating the analytical report, attention 

should be given to the data quality, and the impact of both the 

sampling and analysis data quality to the overall interpretation 

of the analytical results. Both the data from the field QA 

samples and the laboratory QA samples should be evaluated for the 

presence of contaminants. Additionally, statistical procedures 

should be used for the deCe.mination of precision, accuracy and 

completeness. The QApP 1983 document provides a description of 

the statistical procedures and their applications. All reports 

of analytical data should contain a separate section ;crhich 

assesses zhe quality of the reported data. 

The sample procedures and frequency section of the quality 

assurance plans should address, among other elements, sample 

hoiding times, sample preservation procedures, and sample 

chain-of-custody. Maximum sample holding times are presented in 

Tabie 2.4. Section 2.5.3 addresses sample preparation. Section 

2.7.2 addresses sample chain-of-custody. 

The section of the quality assurance plan on internal 

quality control checks specifically discuss how the following 

activities sill be addressed: 

4-5 
Qruanic Prioritv Pollutants 

0 Instrument tuning and calibra 

0 Method blank analysis 

0 Surrogate spike analysis 

0 Matrix spike/matrix spike dup 

0 Internal standards analysis 

tion 

licate analysis 

Inorganic Prioritv Pollutants 

0 Initial calibration verification 

0 Continuing calibration verification 

0 InstrumeIlt response and linearity verifica,tion 

0 Calibration and preparation blank analyses 

0 Interference check sample analyses 

0 Spike sample analyses 

0 Duplicate sample analyses 

0 Quality control sample analyses 

0 Serial dilution analyses (if applicable) 

0 Instrument detection limit determination 

0 Method of standard additions application. 

4-6 
5. SAMPLING AND ANALYTICAL COSTS 

The cost of carrying out a sludge sampling program can vary 

depending on the number and type of samples, parameters analyzed, 

and whether analytical services are contracted out. The 

following discussion examines sampling and analytical costs as of 

April 1989. 

5.1 MANPOWER REQUIREMENTS 

Manpower requirements fall into two categories: (1) 

supervisory and program development, and (2) sampling/analytical. 

All sampling programs should be designed and supervised by 

qualified personnel. Developmental and supervisory needs will 

vary according to the following factors: 

• Type and number of samples 

• Number of streams to be sampled 

• Number of facilities/locations 

• Availability of suitable sample points 

• Parameters to be analyzed 

• Experience and qualifications of field and laboratory 

personnel. 

The number of factors influencing supervisory needs makes 

estimating average Costs for these needs impractical. Costs will 

vary according to the hours needed for each program and according 

to the salary range of qualified personnel within a given 

organization. 

Sampling manpower needs will also vary widely depending on 

the conditions listed above. For 24-hour composite sampling, a 

5-1 
minimum of two shifts (more likely three) are required. The 

actual time spent sampling during the shifts will depend on how 

frequently grab samples are collected (one per hour or once every 

4 hours) during the 24-hour sampling period. In addition to the 

manpower required to actually collect the sample, additional time 

is required for sample preparation and handling. On-the-job 

training is generally acceptable for sampling procedures. 

Estimates of some of these needs are presented below: 

TABLE 5.1 

Activity manpower 

• Automatic Sampler Setup' 0.5 - 4 manhours 

• Sample Container 2- 15 

Preparation2 

man-minutes 

sample 

• Sample Documentation3 2- 15 man-minutes 

sample 

• Sample Handling4 2- 60 man-minutes 

sample 

1 Depending on sample point characteristics. 

2 Depending on parameter. 

3 Depending on parameter, ultimate data use and number of points 

sampled simultaneously. 

4 Depending on parameters sampled and whether samples are 

analyzed on site, are delivered or shipped. 

5.2 IN-HOUSE ANALYTICAL COSTS 

If any analytical work is done in-house, manpower, 

equipment/facility and operating (i.e., electrical, chemical 

supplies, etc.) costs will be incurred. Real costs will vary 

according to what extent the analytical load imposed by the 

sludge sampling is marginal to the laboratory's operational 

5-2 
capacity. Two extremes serve as examples of this cost 

variability. 

A plant electing to do in-house analysis which has no 

laboratory would need to make a sizable expenditure for an 

adequate facility and the necessary analytical equipment and 

supplies. In addition, qualified [B.S. Chemistry or equivalent) 

laboratory personnel must be put on the payroll. Given these 

circumstances, it would generally not be practical to do in-house 

analysis. Instead, it is likely that this plant would contract 

out for analytical services. 

A second plant, conducting a similar sludge sampling 

program, also elects to do all related analytical work in-house. 

This plant, however, has an analytical laboratory in place which 

is capable of performing all analyses required. In addition, the 

laboratory is presently operating below capacity. The additional 

load imposed by the sludge sampling program will not require any 

capital expenditure, and will require little, if any, additional 

laboratory manpower (any additional manpower needs can be 

accommodated by limited overtime rather than new employee hires) . 

In the case of this plant, in-house analysis for a sludge 

sampling program can be accomplished at a very low real cost, 

Because of the wide range of real costs possible for 

sampling and in-house analytical work, no attempt is made herein 

to quantify these costs on a dollars per sample basis. Rather, 

each sampling program must be analyzed in light of applicable 

salary scales, sampling program complexity and in-house 

analytical capabilities. 

5-3 
5.3 CONTRACT ANALYTICAL COSTS 

Many sludge sampling programs, particularly those conducted 

by small municipalities or authorities, will utilize contract 

laboratories for analytical work. In contrast to sampling costs, 

which vary greatly due to a wide variety of factors, contract 

analytical costs. fall within a relatively narrow range. Table 

5.2 presents typical analytical costs for parameters commonly run 

on sludge samples. These cost estimates were obtained in a March 

1988 and 1989 telephone survey of analytical laboratories. 

Two factors must be considered in estimating contract 

analytical costs for sludge sampling programs. The first is tlhe 

need, depending on parameters, for additional preparation of 

sludge samples prior to analysis. Fany laboratories charge an 

additional fee for this preparation, which can be as much as 

$100, depending on the parameters to be run. 

The second factor impacting analytical costs is the practice 

by most laboratories of offering discounts on per sample prices 

for multiple sample analysis. These discounts vary from 

laboratory to laboratory, and can be substantial depending on the 

number of samples involved. Of particular importance is the 

number of samples being received simultaneously by the laboratory 

(i.e., a greater disccunt *Jill typically be offered for 10 sampies if ail are tc be analyzed at one time rather than if one is 

to be delivered to the lab each ;ieek for i0 weeks). 

5.4 SAMPLING EQUIPMENT COSTS 

The cost of sampling equipment and containers is typically a 

relatively small fraction of the overall cost of a sludge 

sampling program. In general, the manual collection methods used 

for sludge sampling require only simple, relatively inexpensive 

5-4 
TABLE 5.2 

TYPICAL CONTRACT ANALYTICAL COSTS FOR 

COMMONLY ANALYZED SLUDGE PARAMETERS 

ANALYSIS COST RANGE ($/SAMPLE) 

Washington District of 

State Columbia California Massachusetts 

Prioritv Pollutants 

Organics Methods: 

1624Cj1625C 

Office of Solid 

Waste #8240 

624-S/625-S 

Acid Fraction Only 

Base Neutral Only 

Metals: 

ICAP or ?AS 

Others: 

Cyanide 

Phenols 

Total PCBs 

2200-2400 

1800-2200 425 550 

N/A N/A 225 

N/A N/A 325 

25-200/metal 

20-30 

20-30 

60-1.50 

250 

240/(13) 

75 

75 

200 

Pesticides included 

in above 

Total for Priority Scan without Dioxin 

2225-5210 1265 

Other Non PriOritv Pollutants 

Oil & Grease 15-25 II total grav. 

v HC 11 

1, EC & tot " 

11 III method 

Ammonia, as N 

Tot Kjeldahl N 

Tot Suspend Sol 

Tot % Solids 

Tot Phosphorus 

Phosphate 

Potassium 

Tot Org Halides 

EP Toxicity 

extraction N,‘A 

8 metals 

2 pest. 

4 herb. 

TOTAL EP $ 420 

10-20 

10-20 

10-29 

IO-29 

10-20 

10-50 

20-30 

50-190 

290/(13) 

60 

50 

i75 

150 

15 27 

60 

80 

130 

100 

35 

35 

15 

15 

35 

35 

15 

80 

100 75 

140 185 

100 150 

150 175 

$490 $585 
equipment. The following paragraphs highlight the primary 

equipment cost items in a typical sludge sampling program. 

0 Sample Containers - Sample container costs are related 

to: (1) the number of containers needed, and (2) the 

type of container needed, depending on parameter(s) to 

be analyzed. The following are typical per-container 

prices for some commonly used containers: 

Container 

Teflon 1 liter s 35 - 40 

Graduated Glass 1 liter s 3-4 

(w/Teflon-lined cap) 

Polypropylene 1 liter .s 2 

Polypropylene 0.5 liter $ 1.50 

Polypropylene 10 liter $ 15 

Glass 0.5 liter S<l-2 

(w/Teflon lined cap) 

Approx. Price 

As with analytical costs, suppliers of containers often 

offer substantial discounts for volume purchases. 

0 Automatic Samplers - In most sludge sampling programs 

the use of automatic sampling equipment will be 

precluded due to sample characteristics. If automatic 

sampling is utilized in a given sampling program, 

automatic sampler costs will typically con.stitTute the 

majority of sampling equipment costs. Portable, 

battery-powered peristaltic-type samplers tlypically 

cost from $1000 to $3000, depending on features such. as 

computerized controls, etc. "neumatically operated 

plunger-type samplers will vary in price according to 

application and capacity. 

0 Manual Sampling Equipment - In general, equipment 

costs for manual sludge sampling are minimal. 

Stainless steel pitchers (2 liter!, which are useful 

for sampling from either a tap or an open channel flow, 

are available for approximately $20. Polypropylene 

pitchers typically cost about l/2 of the price of 

stainless steel. Stainless steel scoops used for 

sludge cake sampling cost approximately $40 CdependLng 

on size), while aluminum scoops of similar size are 

available for less than $10. 

0 Preservatjves - Reagent grade chemicals should be used 

as preservatives. Since each sample will typically 

5-6 
require very small amounts of preservatives, cost on a 

per sample basis is negligible. 

5.5 OPPORTUNITIES FOR COST SAVINGS 

To provide a representation of sludge quality over a fixed 

duration, sewage sludge can be composited (i.e. mixed), reducing 

the number of samples to be analyzed. In light of the high costs 

associated with analysis of priority pollutant organics in sewage 

sludge, cornpositing samples provides an opportunity to 

substantially lower analytical costs. ?ield campositing is not 

an appropriate teclhnique to use when the sample sill Se analyzed 

for volatile components. Lab personnel can composite grab 

samples in the lab. 

When interested in daily variation in sludge constituents, a 

POTW can collect and analyze 24-hour composite samples, each 

consisting of six or more grab samples. This represents a 

significant cost savings when compared to separately analyzing 

many individual, non-composited samples. Smaller POTXs, with 

less variation in sludge quality, may elect to composite samples 

over several days as opposed to 24-hotlr composites. The 

suitability cf a multi-day ccmpositing prxedure w:ll Cepend upon 

whether the specific sludge constituent can be adequately 

preserved in the sludge sample. Table 2.3 shows tkr,e recommended 

preservatives and maximum sample holding times for organic and 

metal pollutants. 

Another way to reduce costs wculd be to sample more 

frequently for parameters that are relatively inexpensive zo 

analyze such as metals, nitrogen, phosphorus, and potassium, and 

to test for organic pollutants (expensive) less frequently, so 

long as some data are available indicating that the levels of 

organic contaminants in the sludge are acceptable. 

5-7 
6. REFERENCES 

APHA-AWWA-WPCF. 1976. "Standard Methods for the Examination of 

Water and Wastewater". Washington, D.C.: APHA-AWWA-WPCF. 

Black, C.A. (ed.). 1965. "Methods of Soil Analysis, Agronomy 

Monograph No. 9." Madison, Wisconsin: American Society of 

Agronomy. 

Colby, Bruce N., and Ryan, Philip W. 1986. "Initial Evaluation 

of Methods 1634 and 1635 for the Analysis of Municipal Wastewater 

Treatment Sludges by Isotope Dilution GC/MS". Washington, D.C.: 

U.S. Environmental Protection Agency, Office of Water Regulations 

and Standards. 

"Criteria for Classification of Solid Waste Disposal Facilities 

and Practices," 40 CFR Part 257. Washington, D.C.: National 

Archives and Records Administration, Office of the Federal 

Register. 

EPA. 1974. "Process Design Manual for Sludge Treatment and 

Disposal", EPA625/1-74-006. Washington, D.C.: U.S. 

Environmental Protection Agency, Office of Technology Transfer, 

EPA. 1976. " Analytical Methods for Trace Metals", 

EPA-430/l-76-002. Cincinnati, OH: U.S. Environmental Protection 

Agency, National Training and Operational Technology Center. 

EPA. 1977. "The Sources and Behavior of Heavy Metals in 

Wastewater and Sludges", EPA-600/2-77-070. Cincinnati, OH: U.S. 

Environmental Protection Agency, Municipal Environmental Research 

Laboratory. 

EPA. 1978a. "Microbiological Methods for Monitoring the 

Environment, Water and Wastes", ETA-600/8-78-017. Cincinnati, 

OH: U.S. Environmental Protection Agency, Environmental 

Monitoring and Support Laboratory. 

EPA. 1978b. "Validity of Fecal Coliforms, Total Coliforms, and 

Fecal Streptococci as indicators of Viruses in Chlorinated 

Primary Sewage Sludge Effluents", EPA-600/J-78-175. Cincinnati, 

OH: U.S. Environmental Protection Agency, Environmental 

Monitoring and Support Laboratory. 

EPA. 1979a. "Methods for Chemical Analysis of Water and Wastes", 

EPA-600/4-79-020. Cincinnati, OH: U.S. Environmental Protection 

Agency, Environmental Monitoring and Support Laboratory. 

6-1 
EPA. 1979b. "Process Design Manual - Sludge Treatment and 

Disposal", EPA 625/l-79-011. Cincinnati, OH: U.S. Environmental 

Protection Agency, Municipal Environmental Research Laboratory. 

EPA. 1981. "Parasites in Southern Sludges and Disinfection by 

Standard Sludge Treatment", EPA-600/2-81-166. Cincinnati, OH: 

U.S. Environmental Protection Agency, Municipal Environmental 

Research Laboratory. 

EPA. 1983a. "Process Design Manual - Land Application of 

Municipal Sludge", EPA-625/l-83-016. Cincinnati, OH: U.S. 

Environmental Protection Agency, Municipal Environmental Research 

Laboratory. 

EPA. 1983b. "Interim Guidelines and Specifications for 

Preparing Quality Assurance Project Plans". PB83-170514, 

QAMS-005/80. Office of Research and Development. 

EPA. 1984a. "Multielemental Analytical Techniques for Hazardous 

Waste Analysis: The State-of-the-Art", EPA-600/4-84-028. Las 

Vegas, NV: U.S Environmental Protection Agency, Environmental 

Monitoring Systems Laboratory. 

EPA. 1984b. "Interim Methods for the Measurement of Organic 

Priority Pollutants in Sludges". Cincinnati, OH: U.S. 

Environmental Protection Agency, Environmental Monitoring and 

Support Laboratory. 

EPA. 1984c. "Development of Analytical Test Procedures for the 

Measurement of Organic Priority Pollutants in Sludge", 

EPA-600/4-84-001. Cincinnati, OH: Environmental Monitoring and 

Support Laboratory. 

EPA. 1984d. "USEPA Manual of Methods of Virology", 

EPA-600/4-84-013. Cincinnati, OH: U.S. Environmental Protection 

Agency, Environmental Monitoring and Support Laboratory, 

EPA. 1986a. "Proceedings: Workshop on Effects of Sewage Sludge 

Quality and Soil Properties on Plant Uptake of Sludge - Applied 

Trace Constituents". Las Vegas, NV: U.S. Environmental 

Protection Agency, Office of Research and Development. 

EPA. 1986b. "Test Methods for Evaluating Solid Waste, SW-846". 

Washington, D.C. : U.S. Environmental Protection Agency, Office 

of Solid Waste and Emergency Response. 

EPA. 1987. "Preparation Aid for HWERL's Category II Quality 

Assurance Project Plans". Cincinnati, OH: U.S. Environmental 

Protection Agency, Office of Research and Development. 

6-2 
EPA. 1988a. 'VAnalytical Methods for the National Sewage Sludge 

Survey". Washington, D.C.: U.S. Environmental Protection 

Agency, Office of Water Regulations and Standards. 

EPA. 1988b. "Draft Guidance for Writing Case-by-Case Permit 

Requirements for Municipal Sewage Sludge". Washington, C.C.: 

U.S. Environmental Protection Agency, Office of Water Enforcement 

and Permits. 

EPA. 1988c. "Strategy for Interim Implementation of Sludge 

Requirements in Permits". Washington, D.C.: U.S. Environmental 

Protection Agency, Office of Water Enforcement and Permits (fin&l 

due August 1989). 

EPA. 1989. flControl of Pathogens in Municipal Wastewater Sludge 

for Land Application". (Draft May 1989, final due August 1989). 

"Guidelines for Establishing Test Procedures for the Analysis cf 

Pollutants,11 40 CFR Part 136. Washington, D.C.: National 

Archives and Records Administration, Office of the Federal 

Register. 

"Memorandum: Pathogen Equivalency Committee," U.S. Environmental 

Protection Agency, Office of Water, November 2, 1987. 

Metcalf and Eddy, Inc. 1979. Wastewater Engineering. 

Treatment, Disposal, Reuse. New York: McGraw-Hill 3ook Company. 

6-3 
APPENDIX A 

CHAIN OF CUSTODY RECORD 
Chain of Custody Record 

Source: 1987 EPA Document "Preparation Aid for HWERL's Category II Quality Assurance Project Plans" 

A-1 
APPENDIX B 

DETERMINATION OF VOLATILE SOLIDS 
DETERMINATION OF VOLATILE SOLIDS 

REDUCTION IN DIGESTION1 

By J.B. Farrell 

INTRODUCTION 

When sewage sludge is utilized on land, Federal regulations require that 

it be treated by a “process to significantly reduce pathogens” (PSRP) or a 

“process to further reduce pathogens” (PFRP). A requirement of both of these 

steps is a reduction in “vector attraction” of the sludge. If the PSRP or 

PFRP is anaerobic or aerobic digestion, the requirement for vector attraction 

reduction is achieved if volatile solids are reduced by 38 percent. As 

Fischer’ has noted, the Federal regulation2 does not specify a method for 

calculating volatile solids reduction. Fischer observed that the United 

Kingdom has a similar requirement for volatile solids reduction for digestion 

(40 percent), but also failed to prescribe a method for calculating volatile 

solids reduction. Fischer has provided a comprehensive discussion of the 

ways that volatile solids reduction may be calculated and their limitations. 

He presents the following equations for determining volatile solids reduction: 

1. Full mass balance equation 

2. Approximate mass balance equation 

3. “Constant ash” equation 

4. Van Kleeck equation 

The full mass balance equation is the least restricted but requires more 

information than is currently collected at a wastewater treatment plant. The 

approximate mass balance equation assumes steady state conditions. The 

“cons tan t ash” equation requires the assumption of steady state conditions as 

well as the assumption that ash input rate equals ash output rate. The Van 

Kleeck equation, which is the equation generally suggested in publications 

originating in the United States3 is equivalent to the “constant ash” 

equation. Fischer calculates volatile solids reduction using a number of 

l Source : “Control of Pathogens in Municipal Wastewater Sludge,” EPA, to be 

published August, 1989. 

B-l 
examples of considerable complexity and illustrates that the different methods 

frequently yield different results. He closes with the recommendation, 

obviously directed to rulemakers, that “if it is necessary to specify a 

particular value for FVSR (fractional volatile solids reduction) then the 

specification should indicate the method of calculation of FVSR.” 

Fischer’s paper is extremely thorough and is highly recommended for 

someone trying to develop a deep understanding of potential complexities in 

calculating volatile solids reduction. However, it was not written as a 

guidance document for field staff faced with the need to calculate volatile 

solids reduction in their own plant. The nomenclature is precise but so 

detailed that it makes comprehension difficult. In addition, two important 

troublesome situations that complicate the calculation of volatile solids 

reduction--grit deposition in digesters and decantate removal--are not 

explicitly discussed. Consequently, this presentation has been prepared to 

present guidance that describes the major pitfalls likely to be encountered in 

calculating volatile solids reduction and assists the practitioner of 

digestion to the best route to take for his situation. 

The recommendation of this presentation is not the same as Fischer's. He 

suggests that the authorities should have provided a calculation method when 

they required specific volatile solids reductions. From a review of Fischer’s 

results and this presentation, it will be clear that sometimes very simple 

calculations will give correct results and in other cases the simple methods 

will yield results seriously in error. Selecting one method and requiring 

that it be followed is excessively restrictive. The best solution is to 

require that the calculation be done correctly and then provide adequate 

guidance. This- presentation attempts, belatedly, to provide that adequate 

guidance. 

It is important to note that the calculations of volatile solids 

reduction will only be as accurate as the measurement of volatile solids 

content in the sludge streams. The principal cause of error is poor sampling. 

Samples should be representative, covering the entire charging and withdrawal 

periods. Averages should cover extended periods of time during which changes 

in process conditions are minimal. For some plants it is expected that 

B-2 
periodic checks of volatile solids reduction will produce results so erratic 

that no confidence can be placed in them. In this case, adequacy of 

stabilization can be verified by the method suggested in the text-- 

periodically batch digest the product for 40 days. If VS reduction is less 

than 15X, the product is sufficiently stable. 

The Equations for FVSR 

The equations for fractional volatile solids reduction (FVSR) that will 

be discussed below are the same as developed by FischerI, except for omission 

of his “constant ash” equation. This equation gives identical results to the 

Van Kleek equation so it is not shown. Fischer’s nomenclature has been 

avoided or replaced with simpler terms. The material balance approaches are 

called “methods” rather than “equations. I’ The material balances are drawn to 

fit the circumstances. There is no need to formalize the method with a rigid 

set of equations. 

In the derivations and calculations that follow, both VS (total volatile 

solids content of :he sludge or decantate on dry solids basis) and FVSR are 

expressed throughout as fractions to avoid the frequent confusion that occurs 

when these terms are expressed as percentages. “Decan ta te” is used in place 

of the more commonly used “supernatant” to avoid the use of “s” in subscripts. 

Similarly, “bottoms” is used in place of “sludge” CO avoid use or’ “s” in 

subscripts. 

The “full mass balance” method 

The “full mass balance” method must be used when steady conditions do not 

prevail over the time period chosen for the calculation. The chosen time 

period must be substantial, at least twice the nominal residence time in the 

digester (nominal residence time = average volume of sludge in the digester + 

average volumetric flow rate. Note: when there is supernatant withdrawal, 

volume of sludge withdrawn should be used to calculate average volumetric flow 

rate). The reason for the long time period is to reduce the influence of 

short-term fluctuations in feed or product flow rates or compositions. If 

input compositions have been relatively constant for a long period of time, 

then the time period can be shortened. 

B-3 
An example where the full mass balance method would be needed is an 

aerobic digester operated as follows: 

1. Started with the digester l/4 full (Time zero). 

2. Raw sludge is fed to the digester daily until digester is full. 

3. Supernatant is periodically decanted and raw sludge is charged into 

the digester until not enough settling occurs to accommodate daily 

feeding. (Hopefully this will not occur until enough days have 

passed for adequate digestion.) 

4. Draw down the digester to about l/4 full (final time), discharging 

the sludge to sand beds. 

The full mass balance is written as follows: 

Sum of total volatile solids inputs in feed streams 

during the entire digestion period = sum of volatile 

solids outputs in withdrawals of decantate and bottoms A 

loss of volatile solids + accumulation of volatile 

solids in the digester. (1) 

Loss of volatile solids is calculated from Equation 1. FVSR- is calculated by 

Equation 2: 

FVSR = loss in volatile solids 

sum of volatile solias inputs (2) 

The accumulation of volatiie solids in the digester is the final volume 

in the digester after the drawdowns times finai volatile solids.concentration 

less the initial volume at time zero times the initial volatile solids 

concentration. 

To properly determine FVSR by the full mass balance method requires 

determination of all feed and withdrawal volumes, initial and final volumes in 

the digester and determination of volatile solids concentrations on all 

streams. In some cases, which will be discussed later, simplifications are 

possible. 

B-L, 
The “approximate mass balance” me thod 

If volumetric inputs and outputs are relatively constant on a daily 

basis, and there is no substantial accumulation of volatile solids in the 

digester over the time period of the test, an approximate mass balance (AMB) 

may be used. The basic relationship is stated simply: 

volatile solids input rate = volatile solids output 

rate + loss of volatile solids. (3) 

The FVSR is given by Equation 2. 

No decantate, no grit accumulation - Calculation of FVSR is illustrated 

for Problem 1 in Table 1 which represents a simple situation with no decantate 

removal and no grit accumulation. An approximate mass balance is applied to 

the digester operated under constant flow conditions. Since no decantate is 

removed volumetric flow rate of sludge leaving the digester equals flow rate 

of sludge entering. Applying Equations 3 and 2, 

FY, = BY, + loss (4) 

Loss r 100 (50-30) = 2000 (5) 

FVSR = Loss (6) 

FYf 

FVSR = 2000 = 0.40 (7) 

(100)(50) 

Nomenclature is given in Table 1. Note that the calculation did not 

require use of the fixed solids concentrations. 

The calculation is so simple that one venders vhy it is so seldom used. 

One possible reason is that the input and output volatile solids concentrations (YF and Y, ) may show greater coefficients of variation (standard 

deviation + arithmetic average) than the fraction volatile solids (VS, 

fraction of the sludge solids that is volatile-- note the difference between VS 

and Y). 

s-5 
Grit deposition - Grit deposition can be a serious problem in both 

aerobic and anaerobic digestion. The biological processes that occur in 

digestion dissolve or destroy the substances suspending the grit and it tends 

to settle. If agitation is inadequate to keep the grit particles in 

suspension they vi11 accumulate in the digester. The approximate mass balance 

can be used to estimate accumulation of fixed solids. 

For Problem 1, the balance yields the folloving: 

FX, = BX, + loss (8) 

(100)(17) = (100)(17) + Fixed Solids Loss (9) 

Fixed Solids Loss = 0 (10) 

The material balance compares fixed solids in output vith input. If some 

fixed solids are missing this loss term vi11 be a positive number. S ince ve 

know that digestion does not consume fixed solids, ve assume that the fixed 

solids are accumulating in the digester. As Equation 10 shows, the f ixed 

solids loss equals zero. Note that for this case, vhere input and output 

sludge flow races -are equal, the fixed solids concentrations are equal ken 

rhere is no grit accumulation. 

The calculation of fixed solids is repeated for Problem 2. Conditions in 

Problem 2 have been selected to show grit accumulation. ?arameters are :he 

same as in Problem 1 except for the fixed solids concentration (X,) and 

parameters related to it. Fixed solids concentration in the digested sludge 

is lover than in ?roblem 1. Consequently, VS is higher and mass flow race of 

solids (input rate = output rate A rate of loss of fixed solids) is presented 

in Equation 11-13. 

Fxf = BX, + Fixed Solids Loss (11) 

Fixed Solids Loss = FX, - BX, (121 

Fixed Solids Loss = (lCO)(l?) - (lOO)(lS) = 200 kg/d (13) 

B-6 
The material balance, which only looks at inputs and outputs, informs us 

that 200 kg/d of fixed solids have not appeared in the outputs as expected. 

We know that fixed solids are not destroyed and conclude that they are 

accumulating in the bottom of the digester. The calculation of FVSR for 

Problem 2 is exactly the same as for Problem 1 (see Equations 4-7) and yields 

the same result. The accumulation of solids does not change the result. 

Decantate vi thdrawal, no grit accumulation - In Problem 3, supernatant is 

withdrawn daily. Volatile and fixed solids concentrations are known for all 

streams but the volumetric flow rates are not known for decantate and bottoms. 

It is impossible to calctllate FVSR vithout knowing the relative volume balance 

and a fixed solids balance, provided it can be assumed that loss of fixed 

solids (i.e., accumulation in the digester) is zero. 

Selecting a basis for F of 100 m’/d, 

Volume balance: 100 = B + D 

Fixed solids balance : 100 Xt = BX, + DX, 

Since the three Xs are known, B and D can be found. 

(II) 

(12) 

Substituting 100-D for B and the values for the Xs from Problem 3 and 

soiving for D and B. 

(100)(17) = (100 -D)(23.50) + (D)(7.24) (13) 

D = 40.0 m3/d, B = 60.0 m3/d (14) 

The FVSR can now be calculated by drawing a volatile solids balance: 

F-f, = BY, + DY, + loss (15) 

loss = FY, - BY, - DY, 

FVSR = - (16) 

FY, F-f: 

FVSR = (100)(50) - (60)(41.42) - (40)(12.76) = 0.40 (17) 

(100)(50) 

Unless information is available on actual volumes of decantate and 

sludge, there Is no way to determine whether grit is accumulating in the 

digester. If it is accumulating, the calculated FVSR will be in error. 

B-7 
When we make the calculation shown in Equation 15-17, we assume that the 

volatile solids that are missing from the output streams are consumed by 

biological reactions that convert them to carbon dioxide and methane. We 

assume accumulation is negligible. Volatile solids are less likely to 

accumulate than fixed solids but it can happen. In poorly mixed digesters, 

the scum layer that collects at the surface is an accumulation of volatile 

solids. FVSR calculated by Equations 15-17 will be overestimated if volatile 

solids accumulation rate is substantial. 

Decantate withdrawal and grit accumulation - In Problem 4, there is 

suspected grit accumulation. The quantity of B and D can no longer be 

calculated by Equations 11 and 12 because Equation 12 is no longer correct. 

The values of B and D must be measured. All parameters in Problem 4 are the 

same as Problem 3 except measured values for B and D are introduced into 

Problem 4. Values of B and D calculated assuming no grit accumulation 

(Problem 3--see previous section) , and measured quantities are compared below: 

B 

D 

Calculated Measured 

60 49.57 

40 50.43 

The differences in the values of B and D are not large but they nake a 

substantial change in the numerical value of FVSR. The FVSR for Problem 4 is 

calculated below: 

FVSR = (100) (50) - (49.57)(41.42) - (50.43)(12.76) = 0.461 

(100)(50) 

(18) 

If it had been assumed that there was no grit accumulation, FVSR ,Jould equal 

0.40 (see Problem 3). It is possible to determine the amount of grit 

accumulation that has caused this change. A material balance on fixed solids 

is drawn: 

Fx, = BX, + DX, + Fixed Solids Loss (19) 

B-8 
The fractional fixed solids loss due to grit accumulation is found by 

rearranging this equation: 

Fixed Solids Loss FX, - BX, - DX, (20) 

FX, = FXf 

Substituting in the parameter values for Problem 4. 

Fixed Solids Loss = (100)(17) - (49.57)(23.50) - (50.43)(7.24) (21) 

FXf (lOO>(li) 

= 0.100 

If this fixed solids loss of 10 percent had not Seen accounted for, :he 

calculated NSR uould have been 13 percent lover than the correct value of 

0.461. Mote that if grit accumulation occurs and it is ignored, calculated 

NSR vi11 be lower than the actual value. 

The Van Kleeck Equa.tion 

Van Kleeck first presented his equation vithout derivation in a footnote 

for a review paper on sludge treatment processing in 1945’. The equation Is 

easily derived from :otal solids and volatile solids mass balances around [Se 

digestion sys tern. Consider a digester operated under steady srate conditions 

with decantate and bottom sludge removal. A total solids mass balance and a 

volatile solids mass balance are: 

M, = M, r M, + (Loss of total solids) (22) 

M;VS, = M;VS, + M;VS, i (Loss of volatile solids) (23) 

The masses must be mass of solids rather than total mass of liquid and solid 

because VS is an unusual type of concentration unit--it is “mass of volatile 

solids per unit mass of total solids.” 

It is now assumed that fixed solids are not destroyed and there is no 

grit deposition in the digester. The losses in Equations 22 and 23 then 

comprise only volatile solids so the losses are equal. It is also assumed 

that the VS of the decantate and of the bottoms are the same. This means that 

the bottoms may have a much higher solids content than the decantate but the 

B-9 
proportion of volatile solids to fixed solids is the same for both streams. 

Assuming then that VS, equals VS, and making this substitution in the defining 

equation for FVSR (Equation 2), 

FVSR = 

Loss of vol. solids = 1 - (Ms + Hd) VS, 

(241 H, l vs, M, a ‘Js, 

From Equation 

solids equals 

% + % 

22, recalling that ve have assumed that loss of total 

loss of volatile solids, 

= Me - loss of vol. solids (25) 

Substituting for H, + nd into Equation 24, 

Wf - Loss of vol. solids) 

FRVS = 1 - 

n: -vs, 

* vs, 

Simplifying further, 

(26) 

FRVS = 1 - (1 - WE+‘JS, 

TS, 

(27) 

Solving for FRVS, 

(23) FRVS = 

vs, - ‘JSj 

VS, - vsc *vs, 

- 

This is the form of the Van Kleeck Equation found in UPCF’s Manual of 

Practice No. 163. Van Kleeck4 presented the equation in the 

following equivalent form: 

FRVS = 1 - 

VS;(l - VS,) 

vs, ‘(I - VS,) 

(29) 

B-10 
The Van Kleeck Equation is applied below to Problems 1-4 in Table 1 and 

compared to the approximate mass balance equation results: 

1 2 3 4 

Approximate Mass Balance (AMB) 0.40 0.40 0.40 O.L6L 

Van Kleeck (VK) 0.40 0.318 0.40 0.40 

Problem 1: No decantate and no grit accumulation. Both methods give 

correct answers. 

Problem 2: No decantate but grit accumulation. VK is invalid and 

incorrect. 

Problem 3: Decantate but no grit accumulation. AMB method is valid VK 

method is valid only if VS, = VS,. 

Problem 4: Decantate and grit acumulation. AHB method valid only if B 

and D are measured. VK method is invalid. 

The Van Kleeck equation is seen to have serious shortcomings when applied 

to certain practical problems. The AHB method can be completely reliable 

whereas the Van Kleeck method is useless under some circumstances. 

Review and Discussion of Calculation Methods and Results 

Complete Mass Balance Method - The compiete mass balance method allows 

calculation of volatile solids reduction of all approaches to digestion, even 

processes where final volumes in the digester ioes not equal initial volume 

and where daily flows are not steady. A serious drawback is the need for 

volatile solids concentration and volumes of all streams added to or withdrawn 

from the digester as vell as initial and final volumes and concentrations in 

the digester . This can be a daunting task particularly for the small plants 

which are most likely to run their digesters in other than steady flow modes. 

For plants of this kind, an “equivalent” method that shows that the sludge has 

undergone the proper volatile solids reduction is likely to be a better choice 

than trying to demonstrate 38 percent volatile solids reduction. An aerobic 

sludge has received treatment equivalent to a 38 percent volatile solids 

reduction if specific oxygen uptake rate is below a specified maximum. 

B-11 
Anaerobically digested sludge has received treatment equivalent to a 38 

percent volatile solids reduction if volatile solids reduction after batch 

digestion of the product sludge for 40 days is less than a specified maximum5. 

Approximate Mass Balance (AMB) Method - The approximate mass balance 

method assumes that daily flows are steady and reasonably uniform in composition, and that digester volume and composition does not vary substantially 

from day to day. Results of calculations and an appreciation of underlying 

assumptions show that the method is accurate for all cases, including vithdrawal of decantate and deposition of grit, provided that in addition to 

composition of all streams the quantity of decantate and bottoms (the digested 

sludge) are known. If the quantities of decantate and bottoms are not known, 

the accumulation of grit cannot be determined. If accumulation of grit is 

substantial and FVSR is calculated assuming it to be negligible, FVSR will be 

lower than the true value. The result is conservative and could be used to 

show that minimum volatile solids reductons are being achieved. 

The Van Kleeck Equation - The Van Kleeck Equation has underlying 

assumptions that should be made clear wherever the equation is presented. It 

is never valid when there is grit accumulation because it assumes the fixed 

solids input equals fixed solids output. Fortunately, it produces a-conservative result in this case. Unlike the AHB method it does not provide a 

convenient way to check for accumulation of grit. It can be used vhen 

decantate is withdrawn provided VS, equals VS,. Just how big the difference 

between these VS values can be before an appreciable error in FVRS occurs is 

unknown, although it could be determined by making up a series of problems 

with increasing differences between the VS values, calculating FRVS using the 

AMB method and a Van Kleeck equation, and comparing results. 

The shortcomings of the Van Kleeck equation are substantial and may 

eventually lead to a recommendation not to use it. However, it has one strong 

point. The VS of the various sludge and decantate streams are likely to show 

much lower coefficients of v.*riation (standard deviation + arithmetic average) 

than volatile solids and fixed solids concentration. Review of data are 

needed to determine how seriously the variation in concentrations affect the 

confidence interval of FVSR calculated by both methods. A hybrid approach may 

B-12 
turn out to be advantageous. The AMB method could be used first to determine 

if grit accumulation is occurring. If grit is not accumulating, the Van 

Kleeck equation could be used. If decantate is withdrawn, the Van Kleeck 

equation still cannot be used unless VS, is nearly equal to VS,. 

Average Values - The concentrations and VS values used in the equations 

will all be averages. For the material balance methods, the averages should 

be weighted averages according to the mass of solids in the stream in 

question. The example below shows how to average the volatile solids concentration for four consecutive sludge additions. 

Volatile Solids 

Addition Volume Concentration 

1 10 m3 50 kg/m3 

2 7 m3 45 kg/m3 

3 15 m3 40 kg/m3 

4 12 m3 52 kg/m3 

Y av = 10 X 50 + 7 X 45 + 15 X 40 + 12 X 52 = 46.3 kg/m3 :3cJ 

10 + 7 + 15 + 12 

For the Van Kleeck equation, :he averages of VS are required. PrOperl!i 

:hey should be weighted averages based on the weight of the foiids in each 

component of the average although an averag e veighted by the volume of tihe 

component or an arithmetic average may be sufficfently accurate if variation 

in VS is small. The following example demonstrates the calculation of ail 

three averages, 

Addition 

1 

2 

3 

4 

Volume 

12 m’ 

8 m3 

13 m3 

10 m3 

Total Solids 

Concentration 

72 kg/m’ 

50 kg/m’ 

60 kg/m! 

55 kg/m3 

vs - 

0.75 

0.82 

0.80 

0.77 

B-13 
Weighted by Mass 

VS av = 12 X 72 X 0.75 + 8 X SO X 0.82 

+ 13 X 60 X 0.80 + 10 X 55 X 0.77 

12 X 72 + 8 X 50 + 13 X 60 + 10 X 5~ = 0.795 

Veighted by Volume 

VS av = 12 X 0.75 + 8 X 0.82 + 13 X 0.80 + 10 X 0.77 

12 + 8 + 13 + 10 = 0.783 

Arithmetic Average 

VS av = 0.75 + 0.82 + 0.80 + 0.77 

4 = 0.785 

In this example the arithmetic average vas nearly as close as the volumeweighted average to the mass-weighted average, vhich is the correct value. 

(311 

(32) 

(33) 
LITERATURE CITED 

1. Fischer, W.J., “Calculation of volatile solids during sludge digestion,” 

p 499-529, in Bruce A. (ed.) “Sewage Sludge Stabilization and 

Disinfection,” pub. for Water Research Centre by E. Borwood Ltd., 

Chichester, England (1984). 

2. U.S. EPA, Code of Federal Regulations, Title 40, part 257 (40 CFR 2571, 

“Part 257--Criteria for Classification of Solid Uaste Disposal Facilities 

and Practices. ” 

3. Water Pollution Control Federation, Manual of Practice No. 16, “Anaerobic 

Sludge Digestion,” pub. Vater Pollution Control Federation, Uashington, DC 

(1968). 

4. Van Kleeck, L.W., Sewage Uorks J., 17 (6), 1240-1255 (1945), “Operation of 

sludge drying and gas utilization units,” Refer to footnote on p 1241. 

5. U.S. EPA, “Technical Support Document: Pathogens,” pub. by EPA’s Office 

of Water Regulation and Standards, Washington, DC (1989). 

a- 15 
TABLE 1 

QUANTITATIVE INFORHATXON FOR EXAHPLE PROBLEM ““’ --. r 

Parameter Symbol 

-- Units Problem Statement Number 

1 2 3 4 

Nominal residence time 9 d 20 20 20 20 

Time period for averages d 60 60 60 60 

Feed Sludge 

Volumetric Elow rate 

Volatile solids concentration 

Fixed solids concentration 

Fraction volatile solids 

Hass flow rate of solids 

Digested Sludge (Bottoms) 

Volumetric flow rate 

Vnlatile solids concentration 

Fixed solids concentration 

Fraction volatile solids 

Hass flow rate of solids 

ml/d 100 100 100 100 

kg/m’ 50 so 50 50 

kg/m’ 17 17 17 17 

kg/kg 0.746 0.746 0.746 0.746 

kg/d 6700 6700 6700 6700 

m’/d 100 100 

kg/m’ 

43.57 

30 30 41.42 41.42 

kg/m’ 17 15 23.50 23.50 

kg/kg 0.638 0.667 0.638 0.638 

kg/d 4700 4500 

Decan tate 

Volumetric flow rate D m’/d 0 0 50.43 

Volatile solids concentration 

Fixed solids concentration 

Fraction volatile solids 

Hass flow rate of solids 

kg/m’ 

kg/m’ 

- 12.76 12.76 

- 7.24 7.24 

kg/kg - 0.638 0.638 

kg/d - 

-------------_ .---- 

1. Co&i’ ions are steady state; all daily Elows arc constant. Volatile solids are not accumulating in the 

digester, altllougtl grit may be settling out in tflc digester. 

2. Numerical values are given at 3 or 4 significant figures. This is unrealistic considering the expected 

accuracy in measuring solids concentrations and sludge volumes. The purpose of extra significant figures 

is !.(I allou more ullrlersrantfable cnmparisiorr:; to he made OE ttle different calculation methods. 

3. All volatile solids concentrat ions are t)ascd on the total solids, not merely on the suspended solid;-. 

B-16